i originally thought the scott catalogs were the "bible" books for stamp collectors...however i'm learning that this is not the case. they are "OK" at best. they are decent enough for U.S. stamps. but there are errors and i'm speaking from personal experience...the pictures or illustrations of an item can be incorrect. scott catalog does correct these errors eventually but this means you should always seek out another reference (i.e. siegel auctions) especially for the more valuable items. i had a 2000 edition of the specialized catalog and the illustration shown for one of a confederate postmaster provisionals was incorrect. it showed a forgery and valued it at over $5,000.00. this was corrected in a later catalog edition. but that means that incorrect illustration had been in all previous catalogs until the correction was made. so a second opinion never hurts. with that in mind, scott catalog is still a great reference for U.S. stamps and it has decent general coverage for other countries but michel, gibbons, yang, and others provide more specialized coverage for other countries..