Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Standard Catalog of World Coins is a series of numismatic catalogs commonly known as the Krause catalogs in the numismatic hobby. They are published by Krause Publications. These massive by-century volumes list by date virtually every coin type, most photographed, with mintage and other information, plus market valuations in 4 to 5 grades. Listings are by denomination rather than series, as in earlier World coin catalogs. The proprietary KM (or K) numbers are widely used; for some countries specialized or earlier systems such as Y (Yeoman) and C (Craig) are given instead. The century format is inconvenient and expensive for many who collect geographically, and date listings are clipped at the century mark. Originally covering 1800-date, the main catalog (first edition 1972) evolved into an annual 20th century-only work, plus separate 17th, 18th, and 19th century volumes which are revised less frequently.