D O C U M E N T 3 0 4 A U G U S T 1 9 2 4 4 7 5 [6]Abram F. Ioffe Dmitry S. Rozhdestvensky (1876–1940), director of the Optical Institute at the University of Leningrad probably Veniamin Kagan (1897–1953), Professor of Differential Geometry at Moscow State University Leonid I. Mandelshtam (1879–1944), lecturer in physics at Moscow State University Petr P. Lazarev (1878–1942), director of the State Institute of Biophysics in Moscow. [7]Paul Ehrenfest was planning to attend a meeting of the Association of Russian Physicists that was to take place 15–20 September in Leningrad (see Doc. 295). [8]Paul Langevin. [9]Abram F. Ioffe’s Polytechnical Institute in Leningrad. Tatiana Ehrenfest. [10]Anna Ehrenfest. [11]Appended upside down at the upper margin of page 3. The secretary was Georges Oprescu (1881–1969).