1. Chief, Identification Branch, Scientific Services Division, Bureau of Alcohol, Tobacco and Fire-arms, Washington, D.C., US.
2. Research student, Forensic Science Department, The George Washington University, Washington, D.C.; U.S. Army Criminal Investigation Command, Ft. Belvoir, Va., US.
3. Forensic chemists, Scientific Services Division, Bureau of Alcohol, Tobacco and Firearms, Washington, D.C., US.