''Haffner og Haagaas'' ("Haffner and Haagaas") was a Norwegian series of textbooks in

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

published in numerous editions between 1925 and 1979, which were the most widely used textbooks in its field in Norwegian secondary schools for half a century. The series was originally edited by

Theodor Haagaas Theodor Christian Petersen Haagaas (15 June 1873, Tistedalen – 25 December 1961, Oslo) was a Norwegian mathematician and private school owner. He was a co-owner of Frogner School and Nissen's Girls' School (1913–1918) and founder, owner ...

and Einar Haffner, for whom it was named. Theodor Haagaas and Einar Haffner were joint editors from 1925 to Haffner's death in 1935, and Haagaas was sole editor from 1935 to 1959. In 1959, Harald Sogn replaced Haagaas as editor. The last editions were edited by Kjell Gjævenes. The series was originally published by H.J. Haffners Forlag, and was later published by N. W. Damm & Søn. Prior to 1940, some editions appeared under the title ''Haagaas og Haffner''.John Solheim, ''125 år: N.W. Damm & Søn 1843–1968: de siste femogtyve år'', Oslo, 1968, p. 46

References

{{reflist Norwegian books