Henry Gray’s Anatomy of the Human Body, commonly known as Gray's Anatomy is one of the classic works on human anatomy.
The 1918 edition of Gray's Anatomy is now in the public domain, and can be used a source for Wikipedia articles. Note, however, that it is almost a century old, and can no longer be regarded as authoritative. Modern medical sources should be used to double-check and update any information from Gray's Anatomy.
Gray's Anatomy is still considered one of the most comprehensive and detailed books of its type in that era and today.