He was particularly friendly with Friedmann and Tamarkin, who were in the class below him at school. Valentina Doinikova, who was a friend of Friedmann, describes how the three went around together while undergraduates at St Petersburg University:
Siya ay lalo na friendly sa Friedmann at Tamarkin, sino ay sa ang klase sa ibaba siya sa paaralan. Valentina Doinikova, na ang isang kaibigan ng Friedmann, na naglalarawan kung paano ang tatlong nagpunta sa paligid ng magkasama habang undergraduates at St Petersburg University: