The book "Greenberg's Pocket Price Guide to Lionel Trains 1901-2004" was authored by Kent Johnson and the Kalmbach Publishing Co. Staff in 2004. It is a paperback book with 320 pages that serves as a valuable resource for collectors and enthusiasts of Lionel trains. The book includes illustrations and provides pricing information for Lionel trains from the years 1901 to 2004, making it a comprehensive guide for those interested in the history, sales, and collectability of these iconic model trains.