About three Leningrad geometers who died in 1941-42 in the besieged Leningrad

We shall talk about the life and work of three Leningrad geometers: about professor O.K. Zhitomirskij (1891-1942), who was one of the organizers Leningrad competitions in mathematics, about the candidate of physical and mathematical sciences I.M. Liberman (1918-1941), and about S.P. Olovyanishnikov (1910-1941), who graduated the mathematical-mechanical faculty of Leningrad State University. The last two were students of A.D. Alexandrov.