How often is the Encyclopedia of Chickens updated?

The Complete Encyclopedia of Chickens, by Esther J.J. Verhoef-Verhallen and Aad Rijs, had been updated four times as of December 2015. The most recent edition was released in 2009.

The fourth edition of the book, which was released in hardcover on July 10, 2009 by Rebo Publishers, has 336 pages, including many full-color illustrations. Its ISBN-10 number is 9036615925, and its ISBN-13 is 978-9036615921.

Other editions of the encyclopedia were published in 2005, 2006 and 2008. The book can be difficult to find, but many online booksellers, including Amazon.com and AbeBooks, or their resellers, seem to stock copies for a variety of prices and in varying condition.