Normally available as a Two Volume Box Set the individual volumes can be purchased separately:

Two Volume Box Set
Publisher: Caister Academic Press
Editor: Matthias J. Reddehase Institute for Virology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany
(with the assistance of Niels A.W. Lemmermann)
Publication date: April 2013
ISBN: 978-1-908230-18-8 (Two Volume Box Set)
Price: GB £300 or US $600 (Two Volume Box Set)
Pages: 1046
Full details: Cytomegaloviruses (Two Volume Box Set)

Volume I Purchased Separately
ISBN: 978-1-908230-19-5 (Volume I only)
Price: GB £180 or US $360 (Volume I only)
Pages: xxiv + 464

Volume II Purchased Separately
ISBN: 978-1-908230-20-1 (Volume II only)
Price: GB £180 or US $360 (Volume II only)
Pages: xviii + 540