The Merck Manual is a vary practical tool for clinical rotations... The Online version of The Merck Manual of Diagnosis and Therapy is even better when your in a hurry. Most disease process are presented in the following format: Definition, Symptoms and Signs, Diagnosis and Treatment.

In 1899, the American drug manufacturer Merck & Co. first published a small book titled Merck's Manual of the Materia Medica. It was meant as an aid to physicians and pharmacists, reminding doctors that “Memory is treacherous.” Compact in size, easy to use, and comprehensive, The Merck Manual (as it was later known) became a favorite of those involved in medical care and others in need of a medical reference. Even Albert Schweitzer carried a copy to Africa in 1913, and Admiral Byrd carried a copy to the South Pole in 1929.

By the 1980s, the book had become the world's largest selling medical text and was translated into more than a dozen languages. While the name of the parent company has changed somewhat over the years, the book's name has remained constant, known officially as The Merck Manual of Diagnosis and Therapy but usually referred to as The Merck Manual and sometimes “The Merck.