19,19E. 1⁄2p Bisects, 1891. Forged surcharge: Malcolm Barton, “The Falkland Islands Bisects of 1891”, The Philatelist, Vol. 40 (January 1974): 98-105. Genuine postmarks: Malcolm Barton, “Cancellations on Falkland Islands Bisects of 1891”, The Philatelist, Vol. 39 (November 1972): 36-42; Scott Classic Specialized Catalog, Note after 19E.
52. 21⁄2p on 2p, 1928. Forged surcharge: Robson Lowe (editor), The Gee-Ma Forgeries, p.10. de Thuin forged surcharge: James M. Chemi, James H. Beal and James T, De Voss (editors), The Yucatan Affair: The Work of Raoul Ch. de Thuin, Philatelic Counterfeiter, p.34.
Fraudulent postmarks. Anon. note, The Philatelist And PJGB, Vol. 1 (August 1991): 171.
11 Madame Joseph fraudulent postmarks, OCT 15/10 to 1949. Derek Worboys and Roger B.West, Madame Joseph Forged Postmarks, pp.48-50.