Papers include Kagan's correspondence, photographs, printed materials and audio tapes. All letters in the collection date from 1938-39, when he had moved his Petropolis operations to Brussels; there are items by Vladislav Khodasevich, Vladimir Nabokov, and Mikhail Osorgin, and others. Among the photographs are pictures of Ivan Bunin, Konstantin Fedin, and Evgeniĭ Zami︠a︡tin. Printed materials consist chiefly of books published by his firms; some of the books are inscribed, for example by Nikolaĭ Berdi︠a︡ev and Lev Karsavin. Included is a lengthy taped interview of Kagan by Marc Raeff in which Kagan discuses his life and publishing activities.

The papers, which primarily concern Shmelev, consist of correspondence, manuscripts, photographs, and printed materials. The correspondence includes photocopies of letters from Petr Struve to Ivan Shmelev, and of letters from Shmelev to one Aleksandr Ivanovich. Manuscripts consist of Kutyrina's memoirs and essays about Shmelev; these draw heavily on correspondence of Shmelev, Ivan Bunin, Konstantin Balḿont, and Thomas Mann. Also included are Kutyrina's memoirs about the October 1917 Revolution in Moscow. Printed materials consist of books by Kutyrina's husband, the writer Ivan Novgorod-Severskiĭ.