Reference Library - Colorimetry of Overprints
| Caswell, L.R. | "Evaluation of Forensic Methods for Overprint Analysis", The Collectors Club Philatelist, Vol. 91, No. 1, January-February 2012, pp. 35-45. |
| Caswell, L.R. | "Evaluation of Forensic Methods for Overprint Analysis", The Collectors Club Philatelist, Vol. 91, No. 1, January-February 2012, pp. 35-45. |