Hi Donnie,
The Scott catalogs will probably be the easiest to use to look up your worldwide stamps. You can also look up the USA stamps in the Scott catalogs. The catalogs are pricy, especially for the most recent edition, but you should be able to look at them at your library. For USA stamps there are some on-line ways to look up your stamps. Here's a neat site for USA stamps...
http://album.dweeb.org/pages/1883_1.htmlYou can also go to the Mystic stamp catalog on-line...
http://www.mysticstampcatalog.com/l.../2009/page/1These can help you identify your USA stamps.
Dave N.
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