This is a reference book and not a cover-to-cover book, at least not for me.
I am very disappointed that for further reading under each entry only one book or website, such as Wikipedia, is listed. The books that make it into inclusion for further reading are such that have a clear homosexual agenda for promoting the idea that a certain artist or politician, etc. is indeed gay. The problem with that is that there should be biographies, autobiographies, letters, and other more reliable resources.
I still think this is a good book and as Sir Ian McKellen says in his foreword: "But if one or two names entered in [the author's] engaging list are doubtful about their inclusion, perhaps they won't, on reflection, object much to being between the sheets with Michelangelo and Armistead Maupin--what could be cozier?"