Complex sentence: Merck publishes The Merck Manuals, a series of medical reference books that includes the "Merck Manual of Diagnosis and Therapy", the world's best-selling medical textbook, and the "Merck Index", a collection of information about chemical compounds.
Split into simpler sentences: Merck publishes The Merck Manuals, a series of medical reference books. These include the "Merck Manual of Diagnosis and Therapy", the world's best-selling medical textbook, and the "Merck Index", a collection of information about chemical compounds.