Bergey's Manual of Systematic Bacteriology: Volume 2: The Proteobacteria [in three sub-volumes]

This second volume is actually made up of 3 'sub-volumes', in a massive 2,816 pages. So the price is better value than it looks.

From the publisher's announcement:

At present, there are roughly 6250 named species of Bacteria, and the Proteobacteria represent the single largest phylum. Encompassing 72 families and including descriptions of 425 genera and over 1875 named species, the volume will be subdivided into three sub-volumes: The Gammaproteobacteria (Part A), The Alphaproteobacteria (Part B) and the Beta-, Delta-, and Epsilonproteobacteria. Also included are new introductory chapters specific to the phylum. The Proteobacteria also represent the most diverse group of bacteria, metabolically and ecologically. Moreover, the Proteobacteria contain many of the clinically relevant species of Bacteria and are of significance in human, animal and plant health. As a result, this volume caters to the broadest audience and the set is an essential reference for the microbiologist. Most importantly, medically important species appear in all three sub-volumes.

From the reviews of the second edition: "Satisfyingly heavy and a pleasure to handle ! Volume 2 of the Second Edition of this highly respected work boasts a combined weight of more than 7 Kg. Their sheer size is a testament to the quantity of information contained inside. ! Each article ! is organized in a standardized way that helps make the information more digestible. ! The updated Manual has a place in all scientific libraries and its importance can only grow as we continue to explore and appreciate the vast prokaryotic diversity surrounding us." (Dawn Field, Microbiology Today, July, 2006)