The Merck Manual of Diagnosis and Therapy, often called simply The Merck Manual, is the world's best-selling medical textbook. First published in 1899, it is now in its 18th (2006) edition.
The Merck Manual is recommended by librarians in standard references such as the "Brandon/Hill selected list of books and journals for the small medical library"medical/index.shtml" target="_blank">http://www.mssm.edu/library/brandon-hill/small_medical/index.shtml, published by the Medical Library Association. It is also one of the cheapest medical textbooks on the Brandon/Hill list.
The Merck Manual is published by _Merck & Co., Inc. but created by an independent editorial board and peer reviewers. In addition to the hard-cover edition, the full text is available free on-line.http://www.merck.com/mmpe/
The Merck Manual is organized, like most internal medicine textbooks, into organ systems, such as heart, lungs, gastrointestinal system, muscular system, etc., dealing with each major disease of that system in turn, in the standard format of diagnosis (symptoms), prognosis and treatment. It condenses all of medical knowledge into 2992 pages, by emphasizing practical information of use to a practicing physician (in contrast to other internal medicine textbooks, like Harrison's Principles of Internal Medicine, which also discuss the mechanisms of disease), and by not giving bibliographic citations.