Stamp catalogs come offer guides to prices, not the final word on them. That rests with stamps dealers, who use the same catalogs to determine their prices.
How to Find the Value of a Stamp: 16 DIY Appraisal Tips
Scott Catalogue of Errors on U.S. Postage Stamps 18th ed
International Stamp Collection Book Stamps from China, France
When is worthwhile to get an expertizing certificate?
International Stamp Collection Book Stamps from China, France
Stamp Collecting Software - EzStamp WORLD Edition with
US Scott #J19 Mint-VF-Hinged POSTAGE DUE w Small Thins, Scott
US Stamps Value Scott Catalogue # 37: 1860 24c Washington
110 Used Classic Stamps, Scott Catalog Value: $16,758.00, W