B51 or B-51 may refer to:
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HLA-B51, an HLA-B serotype
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Bundesstraße 51, a road in western Germany
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Martin XB-51, an American airplane
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Sicilian Defence
The Sicilian Defence is a chess opening that begins with the following moves:
:1. b:Chess Opening Theory/1. e4, e4 b:Chess Opening Theory/1. e4/1...c5, c5
The Sicilian is the most popular and best-scoring response to White's first move 1.e4. Ope ...
, in the Encyclopaedia of Chess Openings
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B51 (New York City bus)
The Metropolitan Transportation Authority (MTA) operates a number of bus routes in Brooklyn, New York, United States; one minor route is privately operated under a city franchise. Many of them are the direct descendants of streetcar lines (see li ...
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