| Baker Numismatics: Photographic image library of coins with doubled dies, repunched mintmarks, over mintmarks, and repunched dates. |
| Collecting Error Coins: Just as nearly every family has its black sheep, virtually every coin series has its failures. These are known as errors or mis-struck coins, and have a following all their own. |
| Combined Organizations of Numismatic Error Collectors of America: National numismatic organization devoted to error and variety collectors. |
| Error Coins Magazine: Monthly magazine devoted to error coin collecting. Available by subscription. |
| Error World: Internet club devoted to error and variety coinage of all kinds. |
| Israel Error Coins: The site focuses on Israeli error coins but also features Canadian, U.S. and others. See bi-metallic errors, coins struck on scrap metal, and others. |
| Jason's Error Coins: Images of a collection of error coins. Wheat cents, Mercury dimes and other assorted. |
| Rotated Die Coin Census: Census for US coins with major die rotation of 90 degrees to 180 degrees. Includes fake error detection and measurement indices. |
| Silver Dollar VAMs: Detailed information on silver dollars, specifically Morgan and Peace Dollar die varieties known as VAMs. |
| World Error Coins: Describes and illustrates dramatically mis-struck foreign coins. Includes information on recognizing various types of error coins as well as articles on how to get started collecting them. |
Classical
