The NORWEGIAN HEAVY WATER SABOTAGE (Bokmål : Tungtvannsaksjonen,
Nynorsk : Tungtvassaksjonen) was a series of operations undertaken by
Norwegian saboteurs during
World War II
World War II to prevent the German nuclear
weapon project from acquiring heavy water (deuterium oxide), which
could have been used by the Germans to produce nuclear weapons . In
1934, at Vemork, Norway,
Norsk Hydro built the first commercial plant
capable of producing heavy water as a byproduct of fertilizer
production. It had a capacity of 12 tonnes per year. During World War
II, the Allies decided to remove the heavy water supply and destroy
the heavy water plant in order to inhibit the German development of
nuclear weapons. Raids were aimed at the 60 MW
Vemork power station at
Rjukan waterfall in
Prior to the German invasion of
Norway on 9 April 1940, the Deuxième
Bureau (French military intelligence) removed 185 kg (408 lb) of heavy
water from the plant in
Vemork in then-neutral Norway. The plant's
managing director, Aubert, agreed to lend the heavy water to France
for the duration of the war. The French transported it secretly to
Oslo , to
Perth, Scotland , and then to France. The plant remained
capable of producing heavy water.
The Allies remained concerned that the occupation forces would use
the facility to produce more heavy water for their weapons programme.
Between 1940 and 1944, a sequence of sabotage actions, by the
Norwegian resistance movement
Norwegian resistance movement —as well as Allied bombing —ensured
the destruction of the plant and the loss of the heavy water produced.
These operations—codenamed Grouse, Freshman, and
Gunnerside—finally managed to knock the plant out of production in
In Operation Grouse , the British
Special Operations Executive
Special Operations Executive (SOE)
successfully placed four Norwegian nationals as an advance team in the
region of the
Hardanger Plateau above the plant in October 1942. The
Operation Freshman was mounted the following month by
British paratroopers; they were to rendezvous with the Norwegians of
Operation Grouse and proceed to Vemork. This attempt failed when the
military gliders crashed short of their destination, as did one of the
Handley Page Halifax
Handley Page Halifax bomber. The other Halifax returned to
base, but all the other participants were killed in the crashes or
captured, interrogated, and executed by the
In February 1943, a team of SOE-trained Norwegian commandos succeeded
in destroying the production facility with a second attempt, OPERATION
Gunnerside was later evaluated by SOE as the
most successful act of sabotage in all of World War II.
These actions were followed by Allied bombing raids. The Germans
elected to cease operation and remove the remaining heavy water to
Germany. Norwegian resistance forces sank the ferry,
SF Hydro , on
Tinn , preventing the heavy water from being removed.
* 1 Technical background
* 1.1 Approaches to developing a weapon
Heavy water production
* 2 Operations to limit German access to heavy water
* 2.1 Pre-invasion efforts
* 2.2 Operations Grouse and Freshman
* 2.3 Operation
* 2.4 Resumed operation and Allied air raids
* 2.5 Sinking the
* 3 Historical perspective
* 4 SOE Norwegian agents involved
* 5 Published histories
* 6 Fiction, film, and video coverage
* 7 References
* 8 External links
The experimental apparatus with which the chemists
Otto Hahn and
Fritz Strassmann discovered nuclear fission of uranium in 1938
Enrico Fermi and his colleagues studied the results of bombarding
uranium with neutrons in 1934. The first person who mentioned the
idea of nuclear fission in 1934 was
Ida Noddack . Four years after
the Fermi publication, in December 1938,
Lise Meitner and Otto Frisch
correctly interpreted the radiochemical experimental results of Otto
Fritz Strassmann as evidence of nuclear fission . News of
this discovery spread quickly among physicists and it was realised
that if chain reactions could be controlled, fission might lead to a
new source of great power. What was needed was a substance that could
"moderate" the energy of neutrons emitted in radioactive decay, so
that they could be captured by other fissile nuclei.
Heavy water and
graphite were the prime candidates for moderating the energy of
Nazi Germany investigated the production of an atomic bomb (see
German nuclear energy project
German nuclear energy project ), a range of options was identified.
Although historical records provide limited detail on the German
decision to pursue the heavy water approach, it became clear after the
war that they had explored the option. Although ultimately
unsuccessful, the approach chosen has been demonstrated to be
Plutonium -239 (239Pu) makes an effective weapons material
(although requiring an implosion-type mechanism as a simpler Thin Man
gun-type bomb is not feasible).
Heavy water has been demonstrated as an effective moderator for
Heavy water may be separated from ordinary water by electrolysis .
APPROACHES TO DEVELOPING A WEAPON
In nuclear weapon development, the main problem is securing
sufficient "weapons grade" material. In particular, it is difficult to
acquire either fissile isotopes of uranium -235 (235U) or of 239Pu.
Weapons grade uranium requires mining, extracting and enriching
natural ore. Alternatively, plutonium can be "bred" in reactors fueled
by unenriched uranium, which requires chemical separation of the 239Pu
Unlike the Allies, who pursued both the enrichment of uranium and the
production of plutonium, German scientists only focused on plutonium
production, as this method was less expensive.
Although the most common isotope of uranium, uranium-238 (238U), can
be used as secondary fissionable material in hydrogen bombs , it
cannot be used as the primary fissile material for an atomic bomb.238U
can be used to produce 239Pu, through the fission of 235U which
produces neutrons, some of which will be absorbed by 238U creating
239U. After a few days the 239U will decay, turning into
The Germans did not examine ultra-pure graphite because they did not
know that the graphite they had tried was too impure to sustain a
chain reaction, and abandoned it as a possible moderator. They instead
settled on the heavy-water -based reactor design. A heavy water
moderated nuclear reactor could be used to do nuclear fission
research, and, ultimately, to breed plutonium from which a bomb could
HEAVY WATER PRODUCTION
Heavy water made by
In normal water, there is only one deuterium atom for every 6400
hydrogen atoms, but deuterium is more prevalent in the residue of
water used as an electrolyte . An analysis of the residues from the
Vemork hydroelectric plant , a large-scale hydrogen production plant
using electrolysis of water for ammonia production, showed a
hydrogen/deuterium ratio of 48, most of the deuterium being bound in
Leif Tronstad , then a lecturer at the Norwegian
Institute of Technology and
Jomar Brun , head of the hydrogen plant
put forward a proposal in 1933, the year heavy water was first
isolated, for a project, which was accepted by
Norsk Hydro and
production started in 1935.
The technology is straightforward.
Heavy water (D2O) is separated
from normal water by electrolysis because the difference in mass
between the two hydrogen isotopes translates into a slight difference
in the speed at which the reaction proceeds. To produce pure heavy
water by electrolysis requires a large cascade of electrolysis
chambers, and consumes large amounts of power. Since there was excess
power available, heavy water could be purified from the existing
electrolyte. As a result,
Norsk Hydro became the heavy water supplier
for the world's scientific community, as a by-product of fertilizer
production, for which the ammonia was used.
Hans Suess was a German adviser to the production of heavy water.
Suess had assessed the
Vemork plant as being incapable of producing
militarily useful quantities of heavy water in less than five years at
its then capacity.
OPERATIONS TO LIMIT GERMAN ACCESS TO HEAVY WATER
French research considered production of 239Pu using both heavy water
and graphite moderated reactors. Preliminary French research indicated
that the graphite which was then available commercially was not pure
enough to serve the purpose, and that heavy water would be required.
The German research community had reached a similar conclusion and in
January 1940 had procured additional heavy water from Vemork. The
IG Farben , which was a partial owner of Norsk Hydro, had
ordered 100 kg (220 lb)/month; Norsk Hydro's maximum production rate
was then limited to 10 kg (22 lb)/month.
In 1940, the "
Deuxième Bureau " (French military intelligence)
directed three French agents, Captain Muller and Lieutenants Mossé
and Knall-Demars, to remove the world's extant supply, 185 kg (408 lb)
of heavy water from the
Vemork plant in then-neutral Norway. The Norsk
Hydro General Director,
Axel Aubert , agreed to lend the heavy water
to France for the duration of the war, observing that if Germany won
the war, he was likely to be shot. Transportation was difficult as
German Military Intelligence (the
Abwehr ) maintained a presence in
Norway and had been alerted of ongoing French activities in Norway
(although they had not been specifically warned about heavy water).
Had they become aware of the shipment, they might have attempted to
intercept it. The French transported it secretly to
Oslo , to Perth ,
Scotland and then to France.
When France was invaded the French nuclear scientist Frédéric
Joliot-Curie took charge of the material, hiding it first in a Banque
de France vault and then in a prison. Joliot-Curie then moved it to
Bordeaux , where it, plus research papers and most of the scientists
(Joliot-Curie remained in France) boarded the British tramp steamer
Broompark , which was one of the many merchant ships involved in
saving over 200,000 troops and civilians in the three weeks after
Dunkirk . The ship already had industrial diamonds, machinery and a
number of British evacuees aboard. SS Broompark delivered its
passengers and cargo, together with all of the free supply of heavy
water, to Falmouth on 21 June. The award of an OBE to Captain Paulsen
was recorded in the London Gazette of 4 February 1941. Crucial to the
success of the mission was the role played by Charles Howard, 20th
Earl of Suffolk .
Although the ready inventory of heavy water was removed, the plant
remained capable of producing heavy water. In investigations of
collaboration launched by Norwegian authorities after the war, Norsk
Hydro management's collaboration with the Germans was considered.
General Director Aubert's cooperation with the French aided the Norsk
OPERATIONS GROUSE AND FRESHMAN
Operation Freshman Map showing
Møsvatn (west, upstream) and Lake
Destruction of the
Vemork plant was mounted by the Combined
Operations Headquarters in November 1942. The plan consisted of two
operations: the first would drop a number of Norwegian locals into the
area as an advance force, and once they were in place a party of
British engineers would be landed by military glider to attack the
On 19 October 1942, a four-man team of
Special Operations Executive
(SOE)-trained Norwegian commandos parachuted into Norway. From their
drop point in the wilderness they had to ski a long distance to the
plant, so considerable time was given to complete this part of the
mission, known as Operation Grouse. This plan, unlike prior failures,
included the team's studying and memorising blueprints.
Once the Norwegian Grouse team managed to make contact with the
British, the British were suspicious, as they had not heard from the
SOE team for a long time: they had been dropped at the wrong place and
had gone off course from there several times. The secret question took
the form of: "What did you see in the early morning of (a day)?" The
Grouse team replied: "Three pink elephants." The British were ecstatic
at the success of the Norwegian team's insertion, and the next phase
of operations commenced.
On 19 November 1942,
Operation Freshman followed with the planned
glider-borne landing on frozen lake
Møsvatn near the plant. Two
Airspeed Horsa gliders, towed by
Handley Page Halifax
Handley Page Halifax bombers, each
glider carrying two pilots and 15
Royal Engineers of the 9th Field
1st British Airborne Division , took off from RAF Skitten
near Wick in
Caithness . The towing of gliders had always been
hazardous, but in this case it was made worse by the long flying
Norway and poor weather conditions which severely
restricted visibility. One of the Halifax tugs crashed into a
mountain, killing all seven aboard; its glider was able to cast off,
but crashed nearby, resulting in several casualties. The other Halifax
arrived at the area of the landing zone, but although the conditions
had substantially improved it was impossible to locate the landing
zone itself, owing to the failure of the link between the Eureka
(ground) and Rebecca (aircraft) beacons. After much endeavour and with
fuel running low, the Halifax pilot decided to abort the operation and
return to base. Shortly afterwards, however, the tug and glider
combination encountered heavy cloud and in the resulting turbulence
the tow rope broke. The glider made a crash landing, not far from
where the other glider had come down, similarly inflicting several
deaths and injuries. The Norwegians were unable to reach the crash
sites in time, and the survivors eventually came into the hands of the
Gestapo , who tortured them during interrogation (not sparing the
badly injured) and later had them executed under
Adolf Hitler 's
Commando Order .
The most important consequence of the unsuccessful raid was that the
Germans were now alerted to a determined Allied interest in their
heavy water production.
The Norwegian Grouse team thereafter had a long arduous wait in their
mountain hideaway, subsisting on moss and lichen during the winter
until, just before
Christmas , a reindeer was encountered.
A reconstruction of the Operation
Gunnerside team planting
explosives to destroy the cascade of electrolysis chambers
British authorities were aware the Grouse team was still operational,
and decided to mount another operation in concert with them. By this
time the original Grouse team was being referred to as SWALLOW. On the
night of 16 February 1943, in Operation
Gunnerside (named after the
village where SOE head Sir Charles Hambro and his family used to shoot
grouse), an additional six Norwegian commandos were dropped by
parachute by a Halifax bomber of 138 Squadron from
RAF Tempsford .
They were successful in landing, and encountered the Swallow team
after a few days of searching on cross country skis. The combined team
made final preparations for their assault, which was to take place on
the night of 27/28 February 1943.
Supplies required by the commandos were dropped with them in special
CLE containers . (One of these was buried in the snow by a Norwegian
patriot to hide it from the Germans; he later recovered it and in
August 1976 handed it over to an officer of the British Army Air Corps
, which was conducting exercises in the area. The container was
brought back to England and was displayed in the Airborne Museum at
Aldershot . The museum closed in 2008 and is now part of the Imperial
War Museum Duxford ).
Following the failed Freshman attempt, the Germans put mines,
floodlights, and additional guards around the plant. While the mines
and lights remained in place, security of the actual plant had
slackened somewhat over the winter months. However, the single 75 m
(246 ft) bridge spanning the deep ravine, 200 m (660 ft) above the
Måna , was fully guarded.
The force elected to descend into the ravine, ford the icy river and
climb the steep hill on the far side. The winter river level was very
low, and on the far side, where the ground levelled, they followed a
single railway track straight into the plant area without encountering
any guards. Even before Grouse landed in
Norway , SOE had a Norwegian
agent within the plant who supplied detailed plans and schedule
information. The demolition party used this information to enter the
main basement by a cable tunnel and through a window. Inside the plant
the only person they came across was the Norwegian caretaker
(Johansen), who was very willing to cooperate with them.
The saboteurs then placed explosive charges on the heavy water
electrolysis chambers, and attached a fuse allowing sufficient time
for their escape. A
Thompson submachine gun
Thompson submachine gun was purposely left
behind to indicate that this was the work of British forces and not of
the local resistance, in order to try to avoid reprisals. A bizarre
episode ensued when fuses were about to be lit: the caretaker was
worried about his spectacles which were lying somewhere in the room
(during the war new glasses were nearly impossible to acquire). A
frantic search for the caretaker's spectacles ensued, they were found
— and the fuses lit. The explosive charges detonated, destroying the
The raid was considered successful. The entire inventory of heavy
water produced during the German occupation, over 500 kg (1,102 lb),
was destroyed along with equipment critical to operation of the
electrolysis chambers. Although 3,000 German soldiers were dispatched
to search the area for the commandos, all of them escaped; five of
them skied 400 kilometres to
Sweden , two proceeded to
Oslo where they
Milorg , and four remained in the region for further work
with the resistance.
RESUMED OPERATION AND ALLIED AIR RAIDS
Although this attack did no irreparable damage to the plant, it did
stop production for several months. The
Vemork plant was restored by
April and SOE concluded that a repeat commando raid would be extremely
difficult, as German security had been considerably improved.
Almost as soon as production restarted, the USAAF started a series of
raids on Vemork. In November, the plant was attacked by a massed
daylight bombing raid of 143 B-17 heavy bombers dropping 711 bombs, of
which at least 600 missed the plant. The damage, however, was quite
Then, on November 16 and 18, 35 B-24 heavy bombers from the 392nd
Bomber Group based in Wendling, Station 118, attacked the
hydro-electric power station at
Rjukan with excellent coverage of the
target. These missions were the longest for this bomber group, lasting
9 1/2 and 10 1/2 hours respectively.
The need for ground assaults was reduced from a year earlier as there
was now an available alternative of night bombing, which had
previously been unrealistic owing to German air cover. The Germans
were convinced that air raids would result in further serious "hits",
and they decided to abandon the plant and move remaining stocks and
critical components to Germany in 1944.
SINKING THE SF HYDRO
SF Hydro at
Mæl in 1925
Knut Haukelid , who was the only trained commando in the immediate
area, was informed of the German plan to remove the heavy water and
advised he would have to muster support and destroy the shipment. He
recruited two people. They decided to sabotage a ferry that would be
carrying the heavy water across Lake
Tinn . One of the people he
recruited recognised a ferry crew member and talked to him, taking
this advantage to slip into the bottom of the ship and plant the bomb,
after which he slipped away. Eight and a half kilograms of plastic
explosive with two alarm-clock fuses were fixed to the keel of the
SF Hydro , which was to carry the railway cars with the heavy
water drums across Lake Tinn. On 20 February 1944, shortly after
setting off around midnight, the ferry and its cargo sank in deep
water, finally capping the original mission's objective and halting
Germany's atomic bomb development programme. A number of Norwegian
civilians were killed as the ferry sank. Witnesses reported seeing
steel drums floating after the sinking, leading to speculation that
they did not really contain heavy water, but an examination of records
after the war showed that some barrels were only half full, and
therefore would have floated. A few of these may have been salvaged
and transported to Germany.
In 2005, an expedition retrieved a barrel (numbered "26") from the
bottom of the lake. Its contents of heavy water matched the
concentration noted in the German records, and confirmed that the
shipment was not a decoy. However, it also supported the notion that
the concentration of heavy water in a number of the barrels was too
small to be of value to a weapons program. This might explain the
absence of heavy security measures around the shipment, including why
the ferry itself was not searched for delayed charges. In the film
Telemark , the locomotive and train is shown, somewhat
implausibly covered with German soldiers. In the Ray Mears BBC
coverage, it is stated that in fact the General in command had ordered
this specific disposition of troops.
Unknown to the saboteurs, a "Plan B" had been established by the SOE,
who arranged a second team to attack the shipment at
the first attempt fail. The disassembled factory was later found in
southern Germany during the closing stages of the war by members of
Alsos Mission nuclear seizure force.
The Hydroelectric Plant in 2008. The Hydrogen Production Plant
building was demolished in 1977.
Recent investigation of production records at
Norsk Hydro and
analysis of an intact barrel that was salvaged in 2004 revealed that
although the barrels in this shipment contained water of pH
14—indicative of the alkaline electrolytic refinement process, they
did not contain high concentrations of D2O. Despite the apparent size
of shipment, the total quantity of pure heavy water was limited, with
most barrels only containing between 1/2–1% pure heavy water,
confirming the success of the Operation
Gunnerside raid in destroying
the higher purity heavy water. The Germans would have needed a total
of about 5 t (5.5 short tons) of heavy water to get a nuclear reactor
running; while the manifest indicated that there was only 500 kg (0.55
short tons) of heavy water being transported to Germany. Hence the
Hydro was carrying too little heavy water to supply one reactor, let
alone the 10 or more tons of heavy water needed to make enough
plutonium for a nuclear weapon.
With the benefit of hindsight, the consensus on the German wartime
nuclear program is that it was a long way from producing a bomb, even
if the Norwegian heavy water had been produced and shipped at the
maximum rate. Nevertheless, the unsuccessful British raid (Freshman)
and the feats of the Norwegian saboteurs (Swallow, Grouse, Gunnerside)
made the top secret war against the heavy water production
internationally known and the saboteurs national heroes.
SOE NORWEGIAN AGENTS INVOLVED
The first agent inside the plant
Einar Skinnarland The
Arne Kjelstrup Knut Haugland
Claus Helberg The
Gunnerside Team Joachim Holmboe Rønneberg Knut
Hans Storhaug Birger
Leif Tronstad ) (planner, in the United Kingdom) The
Knut Haukelid , alias "Bonzo" Knut Klonteig Knut
Lier-Hansen Rolf Sørlie (local resistance)
Einar Skinnarland (base
Gunnar Syverstad (plant lab assistant) Kjell
Nielsen (plant transport manager) ("Larsen") (senior plant engineer)
(NN) (car procurer and driver)
As of November 2015, Joachim Rønneberg, age 96, was the last
surviving member of the
Gunnerside team. The New York Times reported
that Rønneberg was "still mentally sharp at his advanced age and
still possessed of the unflappable calm that so impressed British
military commanders more than 70 years ago".
A 1962 book by John D. Drummond, titled But For These Men (ISBN
0705700453 ), tells a true account of two dramatic raids: one on the
Norsk Hydro heavy water factory at Vemork, and another on the railway
ferry "Hydro" to destroy Germany's heavy water production efforts.
The book The Real Heroes of Telemark: The True Story of the Secret
Mission to Stop Hitler's Atomic Bomb by Ray Mears , published by
Hodder & Stoughton 2003 (ISBN 0-340-83016-6 ) describes the events
from the perspective of the unique survival skills of the Norwegian
commandos. It accompanied a
BBC television documentary series, The
Real Heroes of
Telemark , which sticks more to the facts than the film
it is named after. It also describes the survival aspects of the
attack: how to survive for months in a mountain cabin.
The book Skis Against the Atom (ISBN 0-942323-07-6 ) is a first-hand
Knut Haukelid , one of the
Gunnerside raiders who stayed
Jens-Anton Poulsson (Swallow/Grouse) has told the story in the book
The Heavy Water Raid: The Race for the Atom Bomb 1942–1944, Orion
forlag As (2009), ISBN 978-82-458-0869-8 .
Operation Freshman is covered extensively in two books:
Richard Wiggan's Operation Freshman: The
Rjukan Heavy Water Raid 1942,
William Kimber & Co Ltd (1986), ISBN 978-0-7183-0571-0 , and the more
recent, Jostein Berglyd's Operation Freshman: The Actions and the
Aftermath, Leandoer "> The première of Kampen om tungtvannet on 5
February 1948. From left:
Knut Haukelid ,
Joachim Rønneberg , Jens
Anton Poulsson (shaking hands with King Haakon VII ),
Kasper Idland .
A 1948 Norwegian film based on Operations Freshman and Grouse, called
Kampen om tungtvannet , features performances by at least four of the
original participants in the raid.
A 1965 British film based on the Operation
Gunnerside raid, titled
The Heroes of
Telemark . It features a performance by one of the
original participants in the raid – as the Nazi pursuer of the
A 1966 book by Czech author
František Běhounek , titled Rokle u
Rjukanu (Gorge at Rjukan), is a fiction inspired by the events.
A 1979 Canadian movie and TV-series titled A Man Called Intrepid,
based on the book of the same name by William Henry Stevenson . It
David Niven ,
Michael York and
Barbara Hershey .
On November 8, 2005, the
Corporation for Public Broadcasting
Corporation for Public Broadcasting – WGBH
Educational Foundation in Boston, MA aired a program which documented
the work of a team of underwater archaeologists exploring the sunken
SF Hydro in Lake Tinn.
In 2013, for the 70th anniversary of Operation Gunnerside,
interviewed Joachim Rønneberg, the leader and last surviving member
A six-episode TV mini-series titled
The Heavy Water War (The
Saboteurs in the UK) tells the story with a particular emphasis on
the role of
Leif Tronstad . This Norwegian-Danish-British
co-production is in 6 episodes, the first of which was initially
broadcast on 4 January 2015.
* ^ A B C D E Dahl, Per F (1999).
Heavy water and the wartime race
for nuclear energy. Bristol: Institute of Physics Publishing. pp.
103–108. ISBN 07 5030 6335 . Retrieved 12 July 2009.
* ^ Foot, M.R.D. (October 1984). The
Special Operations Executive
BBC Books. ISBN 0-563-20193-2 .
* ^ E. Fermi, E. Amaldi, O. D'Agostino, F. Rasetti, and E. Segrè
(1934) "Radioacttività provocata da bombardamento di neutroni III,"
La Ricerca Scientifica, vol. 5, no. 1, pages 452–453.
Ida Noddack (1934) "Über das Element 93," Zeitschrift für
Angewandte Chemie, vol. 47, no. 37, pages 653–655.
* ^ Weintraub, Bob.
Lise Meitner (1878–1968): Protactinium,
Fission, and Meitnerium. Retrieved on June 8, 2009.
* ^ Bernstein, Jeremy (2007). Plutonium: A History of the World\'s
Most Dangerous Element. Joseph Henry Press. ISBN 0-309-10296-0 .
Retrieved 12 July 2007.
* ^ Powers, Thomas (1993). Heisenberg's War: the secret history of
the German bomb. Alfred A. Knopf. ISBN 0-394-51411-4 .
* ^ The heavy water concept was perfectly viable—one needs only
consider the heavy water moderated production reactors at Savannah
River Site 's R-Reactor, P-Reactor, L-Reactor, K-Reactor, and
Mayak 's production reactors, to see compelling proof
that heavy water is fully effective for plutonium production if
available in sufficient quantities.
* ^ Per F. Dahl (1999).
Heavy water and the wartime race for
nuclear energy. p. 43. ISBN 0-585-25449-4 .
* ^ "
Vemork Heavy Water Plant – 1942–44". GlobalSecurity.org.
Retrieved 15 July 2009.
* ^ Ebb and Flow, Evacuations and Landings by Merchant Ships in
World War Two, Roy Martin ISBN 0955744121
* ^ Andersen, Ketil Gjølme G. (2009). "
Axel Aubert – utdypning".
Store norske leksikon
Store norske leksikon (in Norwegian). Oslo: Kunnskapsforlaget.
Retrieved 7 July 2009.
* ^ A B C D E F G H I Gallagher, Thomas (2002). Assault In Norway:
Sabotaging the Nazi Nuclear Program. Guilford, Connecticut: The Lyons
Press. ISBN 1-58574-750-5 . Retrieved 12 July 2009.
* ^ A B C Berglyd, Jostein; Translated by Tim Dinan (2008).
Operation Freshman: The Hunt for Hitler\'s Heavy Water. Solna:
Leandoer and Eckholm. ISBN 978-91-975895-9-8 . Retrieved 12 July 2009.
* ^ A B Riste, Olav ; Nøkleby, Berit (1970).
Norway 1940–45: The
Resistance Movement. Oslo: Tano. ISBN 82-518-0164-8 .
* ^ "AIRBORNE FORCES MUSEUM IN ALDERSHOT". Airborne Assault
ParaData. Retrieved 3 February 2017.
* ^ The Saboteurs of Telemark,
* ^ Crowdy, Terry (2008) SOE Agent:Churchill's Secret Warriors. pg
* ^ Bailey, Roderick (2008) Forgotten Voices of the Secret War: An
Inside History of
Special Operations in the Second World War, pg
* ^ A B Rhodes, Richard (1995). The making of the atomic bomb.
Simon & Schuster. ISBN 978-0-684-81378-3 . Retrieved 12 July 2009.
* ^ http://www.b24.net The Official Website of the 392nd Bomb Group
* ^ Haukelid, Knut (1989). Skis against the atom. Minot, North
Dakota: North American Heritage Press. ISBN 0-942323-07-6 .
* ^ "Heroes of
Telemark accompany heavy water barrel to USA". Norsk
Hydro ASA. November 23, 2006. Archived from the original on May 27,
2009. Retrieved 15 July 2009. )
* ^ A B "NOVA: Hitler\'s Sunken Secret". The Corporation for Public
Broadcasting – WGBH Educational Foundation. 1996–2005. Retrieved
12 July 2009.
* ^ A B
BBC TV documentary about the raid based on the survival
skills, who actually interviewed the saboteur / "pursuer"
* ^ "KULTURHISTORISK STEDSANALYSE FOR TINN OG NOTODDEN KOMMUNER"
(PDF). p. 34.
* ^ A B NOVA (November 8, 2005). "Hitler\'s Sunken Secret
(transcript)". NOVA Web site. Retrieved 2008-10-08.
* ^ https://www.pbs.org/wgbh/nova/military/nazis-and-the-bomb.html
* ^ Higgins, Andrew (20 November 2015). "WWII Hero Credits Luck and
Chance in Foiling Hitler\'s Nuclear Ambitions". The New York Times.
Retrieved 4 February 2016.
* ^ Rhodes, Richard (1986). The Making of the Atomic Bomb. New
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