Science at the cross roads. Papers presented to the international congress of the history of science and technology, held in London from June 29th to July 3rd, 1931 by the delegates of the U.S.S.R. [With contribs of N.I. Bucharin (N.I. Bukharin), A.F. Joffe, M. Rubinštejn (M. Rubinstein) a.o.] (Kniga, 1931)