Book excerpt: John Castagno's Artists' Signatures and Monograms have become the standard reference source for galleries, museums, libraries, and collectors around the world. Whether used to identify, authenticate, or verify signatures and works of both well-known and little-known artists, Castagno's work has no equal. In the first volume of European Artists Signatures and Monograms, 1800-1990 (Scarecrow, 1990), Castagno provided identification for more than 4,800 artists' signatures, along with biographical information and reference sources. The second volume, published by Scarecrow in 2007, identified an additional 2,100 artists and featured 3,000 signature examples. This third volume features an additional 2,800 artists and signatures. In addition to the standard signature entries, the book features sections for monograms and initials, common surname signatures, alternative surname signatures, and illegible signatures. Less than five percent of the entries in this volume are listed in the original volumes--and these are included to provide additional information about the artists. The use of European Artists III: Signatures and Monograms From 1800, A Directory provides the researcher a reference tool not duplicated elsewhere--one that will save many hours of research.