SHOW MENUPerfins
Burkhart BEER and Maurice HARP, Pilfering, Protection and Perfins: An Aspect of the Line‑Engraved Twopence. Dusseldorf, Germany: Briefmarkenfreunde Dsseldorf, 1996.
Tony EDWARDS and B. C. LUCAS, G.B. Official Perfins. Northwood, Middlesex: The Perfin Society, 1984. 69pp.
Tony EDWARDS, The Tomkins Catalogue of Identified G.B. Perfins. 167pp.
Roy GAULT, The Perfin Society Catalogue of Sloper's Wartime Provisionals.
— The Perfin Society Catalogue of G.B. Perfins – Illustrated Catalogue Updates 1993. The Perfin Society, 1993.
— The Tomkins Catalogue of Identified G.B. Perfins, 7th edition. The Perfin Society, 1993.
Ian HAMILL and Roy GAULT, Great British Perfins found on King George V Seahorses 1913‑1939, 2nd edition. Orpington: Perfin Society, 2017. 142pp.
Ian HAMILL, Kevin PARKHILL, Stephen STEERE and Roy GAULT, The Perfin Society Illustrated Handbook of GB Perfins – Hospital Dies. The Perfin Society, 1993. 28pp.
John S. NELSON, The Handbook of British Perfins, 1st edition. Westerham: John S. Nelson, 1967. 30pp.
— The Handbook of British Perfins, 3rd edition. Northwood, Middlesex: Perfin Society, 1988. 30pp.
— Catalogue of Perfins 1924‑1925 British Empire Exhibition Stamps. The Perfin Society, 1993. 16pp.
Mary E. THORNTON, Catalogue of Official Perfins. Section 1, Great Britain. London: The Great Britain Philatelic Society, 1967. 16pp.
A History of J. Sloper & Co.'s Stamp Security Service. London: J. Sloper & Company 16pp.
