Krause Publications

Krause Publications is a publisher of leisure-time & enthusiast magazines and books. Best known for its Standard Catalog of World Coins, a series of numismatic catalogs commonly referred to as Krause-Mishler catalogues or simply Krause catalogues, they provide information, pricing, and Krause-Mishler (KM) numbers referring to coin rarity and value. Krause-Mishler releases a yearly catalogue of world coins with values and KM numbers. Krause-Mishler numbers are the most common way of assigning values to coins.

-Wikipedia