a chapter in a book
Janet Travell, David Simons, and Lois Simons
Lippincott, Williams & Wilkins
p. xi (2nd edition)
Myofascial trigger points are a frequently overlooked and misunderstood source of the distressingly ubiquitous musculoskeletal aches and pains of mankind.
One article on PainScience.com cites this item as a source: