*[http://www.fas.org/irp/ops/ci/docs/ci1/chap4.pdf A Counterintelligence Reader], Vol. 2, Chap. 4, National Counterintelligence Center (NACIC).
*[http://www.fas.org/irp/ops/ci/docs/ci1/chap4.pdf A Counterintelligence Reader], Vol. 2, Chap. 4, National Counterintelligence Center (NACIC).
*[[Allen Weinstein]], ''The Haunted Wood: Soviet Espionage in America—the Stalin Era'' coauthored with Alexander Vassiliev, (New York: Random House, 1999).
*[[Allen Weinstein]], ''The Haunted Wood: Soviet Espionage in America—the Stalin Era'' coauthored with Alexander Vassiliev, (New York: Random House, 1999).