Reference Library - Gum Analysis
Poslusny, M., and Daugherty, K.E. "A Novel Approach to Looking at Stamps", The American Philatelist, Vol. 104, No. 8, August 1990, pp. 722-726.

Hanneman, W., and Hintze, R. "Gum Characterization by Infrared Spectroscopy", The American Philatelist, Vol. 105, No. 9, September 1991, pp. 816-817.