The papers consist primarily of the Kosatkin-Rostovskiĭ's memoirs. His manuscript memoirs (150 p.) discuss his life up to 1906. Her typescript memoirs (440 p.) discuss her childhood, career as an actress in St. Petersburg, 1917-1918 in Petrograd, and the emigration in France. Also included are his diary for June-July 1940; a few letters written to him; clippings of his newspaper articles (many signed with the pseudonym "Antar"); and a book with his poetry and with essays dedicated to him; "Krestnym putem k voskresenii︠u︡" (Paris, 1948).

The collection contains Simonovich's correspondence, manuscripts, doucments, subject files, and printed materials. There are letters to Simonovich from a friend who had settled in Yugoslavia, A. S. Poplavskiĭ, and Belgian postcards from before World War I. Manuscripts deal with Simonovich's experiences in the Imperial army on the Caucasian front and in the White army under general Slashchev. There are also essays devoted to the Russian emigre colonies in Belgium and in France. The subject files concern the Belgian section of the Gallipolian Society (Obʺshchestvo Gallipolit︠s︡ev) and Russian emigre events in Belgium. The printed materials include chiefly miscellaneous journals and clippings, some with articles by Simonovich.