Referee's report by Max Born, on a paper 'Compressibility and absorption frequency of ionic crystals' by Bela Szigeti Sectional committee: Mathematics Paper reference code: A11 Recommended for publication in Proceedings. 'The paper contains interesting considerations, and the result seems to me correct [...] The subject is somewhat out of date, and would interest only a restricted number of physicists.' Suggests that another referee should give their opinion. [Published in Proceedings A, 1950]. Date received not given. 31 May 1950