Moore, Olin H. The Legend of Romeo and Juliet
Columbus: The Ohio State UP, 1950.

Thesis: Moore has studied all of the possible versions of -- and parallels to -- the Romeo and Juliet story. He concludes that it's possible that Shakespeare used an Italian source to supplement Brooke's Romeus and Juliet. Moore's book is very thorough, and often tedious, but occasionally you find something that sets you to thinking. For instance, in one version when Romeo "attends the Cappelletti ball, his purpose is not to follow his first lady . . . but to find another who will reciprocate his affections" (75-76). If Shakespeare had given his Romeo that motivation, he would have been a more realistic, but much less tragic, character.

Bottom Line: A lot of painstaking scholarship.