American Philatelic Society:  www.stamps.org

Philatelic Foundation: www.philatelicfoundation.org

American Air Mail Society: www.americanairmailsociety.org

American Topical Association: www.americantopicalassn.org

U.S. Philatelic Classics Society: www.uspcs.org

Collectors Club N.Y. : www.collectorsclub.org