Complex sentence: Published in the U.S., Scott catalogs are the accepted standard classification for U.S. and foreign issued stamps; these catalogs are published annually and contain a depiction and price guide for each stamp listed in the catalog.
Split into simpler sentences: Published in the U.S., Scott catalogs are the accepted standard classification for U.S. and foreign issued stamps. These catalogs are published annually and contain a depiction and price guide for each stamp listed in the catalog.