Anatoly Vasilievich Lunacharsky's biographical essays on various leaders including Lenin, Trotsky, Kalinin, Zinoviev as well as Plekhanov and Martov among others.
http://www.marxists.org/archive/lunachar/index.htmFamily response to 'Wolf of the Kremlin: First Biography of L.M. Kaganovich, the Soviet Union's Architect of Fear," a biography of one of Stalin's senior apparatchiks.
http://revolutionarydemocracy.org/rdv1n2/kaganfam.htm