The Philatelic Foundation
Non-profit, specializes in United States stamps.

Professional Stamp Experts
Specializes in United States stamps, leading firm for grading

Confederate Stamp Alliance
Expertizing arm of the Confederate Stamp Society

American Philatelic Society
Expertizing arm of the American Philatelic Society

Vincent Graves Greene Foundation
Canada's premier BNA expertizing service

Worldwide Experts
Website with the most comprehensive list of worldwide philatelic experts we have found

Power Search
Comprehensive search engine containing all of our auctions from 1993 to date, our Rarities sales since their inception in 1964, as well as some important older name sales.

The Siegel Encyclopedia
Informative articles about stamps, and when, how and why they were issued

Census Data
We have compiled comprehensive census information on some of the rarest United States stamps. New information is posted as we complete additional research

Exhibits and Mounted Collections
Exhibits and mounted collections are an excellent way of conveying original research, and of showing different ways of mounting one's collection.

PSE Population Report
Automatically updated weekly, this allows you to determine the population report of any graded Scott number

Siegel Videos
Informative videos about important collections or items we have sold in the past

Today in History
Research whether any important historical events occurred on a certain day

Currency Converter
Convert between any currencies at today's exchange rate. Also contains some historical exchange rate information

The Curtis Collection
Privately maintained census of Revenue multiples. An amazing resource.

Hawaiianstamps.com
Comprehensive website devoted to Hawaiian philately.

U.S. Specimens Blog
A Wordpress blog for the enjoyment of U.S. Specimen stamps

Perpetual Calendar
Useful for dating postal history items

Linn's Stamp News
Weekly Publication

American Stamp Dealer's Association
Main governing body for members of the stamp trade

American Philatelic Society
The largest collector’s organization in the United States. Their site offers links to hundreds of affiliated specialized collecting organizations, and has schedules for upcoming shows.

Royal Philatelic Society of London
Oldest philatelic society in the world. Founded in 1869, permission to use the prefix 'Royal' was granted by His Majesty King Edward VII in 1906. It was ten years earlier that his son, HRH The Duke of York, became President of the Society, an office he continued to hold until his accession to the throne as HM King George V in 1910.

Collector's Club of Chicago
A great resource library from one of America’s leading collector organizations

Carriers and Locals Society
Website devoted to this collecting area, publishers of the Penny Post.

Confederate Stamp Alliance
Premier organization for Confederate philately

U.S. Philatelic Classics Society
Classics Society, a great resource for research on classic U.S. stamps. Publishes The Chronicle, a quarterly publication

The Manuscript Society
An international society whose members cover all fields of autograph collecting.

National Postal Museum
Link to the Smithsonian's National Postal Museum website

The British Library
Link to information about their philatelic collections

James E. Lee
Jim Lee’s website, specializing in philatelic literature

Philatelic Bibliopole
Philatelic literature dealer Leonard Hartmann’s website

Philip Bansner
Phil Bansner’s website, specializing in philatelic literature

James Bendon
Dealer in worldwide philatelic literature