The following web-based resources provide some level of information / insight helpful in conducting research into Swiss philatelic matters.
>> US-based Resources
American Philatelic Research Library
>> Swiss-based Resources
Swiss Postal Stationery Collectors Club
Union of Swiss Philatelic Societies
>> UK-based Resources
Helvetia Philatelic Society (Great Britain)
Museum of Philatelic History (London)
>> Postal Authorities
United Nations Philatelists, Inc.
Switzerland as seen in OECD Data