The Merck Manuals

The Merck Manuals (outside the U.S. and Canada: MSD Manuals) are medical references published by the American pharmaceutical companyMerck & Co. (known as MSD outside the United States and Canada), that cover a wide range of medical topics, including disorders, tests, diagnoses, and drugs. The manuals have been published since 1899, when Merck & Co. was still a subsidiary of the German company Merck.