Encyclopedia of Marks on American, English, and European Earthenware, Ironstone, Stoneware (1780-1980) by Arnold A. Kowalsky, Dorothy E. Kowalsky (1999, Hardcover, Illustrated)

As a collector of English Transferware, I found the vast information in this book to be a tremendous source of reference. The Kowalsky's have not only shown typical back marks, but have created a cross reference guide and timeline for each maker. In addition, an alphabetical list of patterns and other distinguishing features make this a must have book for the collector or dealer.

The main focus does seem to be on the English works, however there are sections of American & European companies as well. This book certainly makes one a more discriminating buyer, as not all is what it seems.