Old World Archaeological Study Unit
Recreation, Collecting, Stamps, Organizations - Old World Archaeological Study Unit. Studies postage issues commemorating aspects of ancient cultures.
http://www.owasu.org/
Auxiliary Markings Club - Postal-Markings.Org
Recreation, Collecting, Stamps, Organizations - Auxiliary Markings Club (AMC). Group studies covers bearing notifications of problems or special services.
https://www.postal-markings.org/
Society for Costa Rica Collectors
Recreation, Collecting, Stamps, Organizations - Society for Costa Rica Collectors. International group interested in the study of the postal history of the Latin American nation.
http://www.socorico.org/
West Africa Study Circle
Recreation, Collecting, Stamps, Organizations - West Africa Study Circle. International society focuses on postal history, particularly of current or former British Commonwealth nations.
http://www.wasc.org.uk/
Pacific Islands Study Circle - Home
Recreation, Collecting, Stamps, Organizations - Pacific Islands Study Circle. For collectors of the stamps and postal history of the smaller Pacific islands.
https://www.pisc.org.uk/
Post Mark Collectors Club
Recreation, Collecting, Stamps, Organizations - Post Mark Collectors Club. International organization to promote the collecting of postmarks and postal history.
http://www.postmarks.org/
First Issues Collectors Club
First issues collectors club promotes the collection of the first postage stamp issued by any nation, province, city, army or other entity that has, at any time, issued postage stamps, and facilitates the exchange of information about these issues among stamp collectors.
http://www.firstissues.org
US Plate Number Coil Collectors Club
Recreation, Collecting, Stamps, Organizations - US Plate Number Coil Collectors Club. The site features photos, data, and values, including newsletter back issues and a section of U.
https://pnc3.org/
Postal history of Hong Kong & Treaty Ports.
Recreation, Collecting, Stamps, Organizations - Hong Kong Study Circle. The SC's web contact point for stamps and postal history of Hong Kong and the Treaty ports.
http://www.hongkongstudycircle.com
India Study Circle for Philately
Recreation, Collecting, Stamps, Organizations - India Study Circle for Philately. Promotes study and research into philatelic and postal history of the Indian subcontinent.
https://www.indiastudycircle.org/
The Rossica Society of Russian Philately
The Rossica Society is a worldwide society devoted to all aspects of Russian philately, from the pre-stamp days of Imperial Russia to current post-Soviet philately. The Society publishes two issues per year of the Award-Winning Rossica Journal which carries information on all facets of Russian stamps and postal history.
https://www.rossica.org/