The European Bibliography of Slavic and East European Studies (EBSEES) - 1991-2007

The European Bibliography of Slavic and East European Studies (EBSEES) collects books, journal articles, reviews and dissertations from Eastern Europe (former countries of Eastern Bloc) which were published in Belgium, Germany, Finland, France, Great Britain, the Netherlands, Austria and Switzerland from 1991 to 2007. The segment "Literature" and "Culture" of the European Bibliography of Slavic and East European Studies contains 18.000 bibliographic entries (from the total asset of 85.000). More information can be found here.

Your search for Ken, Oleg provides 2 hits
1	Karl Radek i Bjuro meždunarodnoj informacii CK VKP(b), 1932-1934 gg. Ken, Oleg, in: Cahiers du Monde russe 44, 2003, pp. 135-78
2	Mobilizatsionnoie planirovanie i polititcheskie resheniïa, koniets 1920-seredina 1930 (Planification de mobilisation et décisions politiques, fin des années 1920-milieu des années 1930) Ken, Oleg H., Saint-Petersbourg, Evropeïskiï Universitet, 2002, 470 p.

The European Bibliography of Slavic and East European Studies (EBSEES) - 1991-2007

Karl Radek i Bjuro meždunarodnoj informacii CK VKP(b), 1932-1934 gg.

Mobilizatsionnoie planirovanie i polititcheskie resheniïa, koniets 1920-seredina 1930 (Planification de mobilisation et décisions politiques, fin des années 1920-milieu des années 1930)