The collection includes correspondence, manuscripts, memoirs, diaries, notes, subject files, documents, photographs, and printed materials. Most of the material in the collection concerns Nikolaev's tenure as military attachʹe at the Russian embassy in Washington. Cataloged correspondents include Mikhail T. Florinsky and Geroid T. Robinson. There is a typescript by Vasiliĭ O. Kli︠u︡chevskiĭ, "Kratkoe posobie po russkoĭ istorii." Among the correspondence are cablegrams and official communications to the Russian embassy during World War I and the revolutionary period. Manuscripts, mostly by Nikolaev, concern contemporary and historical military topics. Diaries and memoirs deal with Nikolaev's travels to Europe during World War I and his activities as military attachʹe. Among orders granted to Nikolaev is the "Order of the Sacred Treasure," signed and sealed by the Japanese Emperor Meiji (1911). Printed materials include many articles by Nikolaev.

The papers consist of correspondence, manuscripts, subject files, photographs, and printed materials. Cataloged correspondents are Mikhail Girs, Robert R. McCormick, Isidor Singer, and Stanley Washburn. Much of the material, including correspondence, reports, and printed materials, concerns German and Russian propaganda in the Japanese War; Russian diplomacy in the first two decades of the century; and Civil War, especially in Siberia. Printed materials include Imperial government publications and also publications of the White government in Omsk.