whether Branson could find: According to Pauling 1955, Branson may have found only one of the two helices, after Pauling explained to him all the important constraints involved. In Pauling 1996, he gives the impression that he (Pauling) had discovered both helices in Oxford and that Branson later confirmed them.

“Polypeptide Chain Configurations”: Bragg, Kendrew, and Perutz 1950.

The idea behind X-ray crystallography: Good descriptions of the technique itself and its applications can be found, eg, in McPherson 2003. An outline containing less physics is Blow 2002.

“Proteins are built of long chains”: Bragg, Kendrew, and Perutz 1950.

Bragg hammered nails: Perutz 1987.