Verenigingen USA
- American Philatelic Society
- The U.S. Philatelic Classics Society
- United States Stamp Society
- American Philatelic Congress
- Plate Number Coil Collectors Club
- Precancel Stamp Society
- American Association of Philatelic Exhibitors
- American Air Mail Society
- United Postal Stationery Society
- American Topical Association
- American First Day Cover Society
- Civil War Philatelic Society
- The American Revenue Association
- United States Possessions Philatelic Society
Verenigingen Canada
- The Royal Philatelic Society of Canada
- The British North America Philatelic Society
- Postal History Society of Canada
- La Société d’histoire postale du Québec
- L’Académie québécoise d’études philatéliques
- The Canadian Aerophilatelic Society
Verenigingen Nederland
- Koninklijke Nederlandse Bond van Filatelistenverenigingen
- Studiegroep Voorafstempelingen
- Perfin Club Nederland
- Postzegelkring Latijns Amerika
Verenigingen Buitenland
- Bundesarbeitsgemeinschaft USA / Canada e.V.
- Canadian Philatelic Society of Great Britain
- Postal Label Study Group
- Auxiliary Markings Club
Zegeluitgiften USA
- Prexie Era Committee
- The Prexies
- Presidential Issue
- US Stamps 1847-2019
- Plating the 3c U.S. Imperforate Stamp of 1851-1857
Zegeluitgiften Canada
- Small Queens for Beginners – A Guide to the Identification of Printings
- Guide to the Admiral Stamps of Canada
- Admiral Constant Plate Varieties
- Elizabethan-era Definitives
- Lowe-Martin Serpentine Die Cutting
Expertise USA
Expertise Canada
Overig USA
- U.S. Postal Service
- American Philatelic Research Library
- Smithsonian National Postal Museum
- US Postal Bulletins and PL&R’s
- World Stamp Show-NY 2016
- Boston 2026 World Stamp Show
- Alaska Statehood Postmarks
Overig Canada
- Canada Post
- Library and Archives Canada
- Canadian Philatelic Bibliography
- The Canadian Stamp Collection
- Chronology of Canadian Postal History
- Postal History Corner
- BNA Proofs
- CAPEX 22