Check out the Billy Squier chapter in Kristofer Engelhart’s 2010 “Beatles-Deeper Undercover.” It is a greatly revised and updated edition of his 1998 book Beatles Undercover. At nearly 400 pages, it painstakingly chronicles The Beatles’ contributions to the work of other artists. Each outside artist’s entry contains a short biography, personal thoughts and memories where possible, and thorough details concerning the exact contribution that John, Paul, George, or Ringo added to their work. Since the original Beatles Undercover, much has been updated and added-without a doubt this is the definitive book on this subject. Available at www.amazon.com