One of my favorite maltese books is "The Maltese: Diminuitive Aristocrat" by Vicki Abbott. I also have a copy of "The Irrepressible Toy Dog" by Darlene Arden that is very good...it is not specific to maltese but it gives a nice overview of toy breeds in general.
I'm sure others will chime in with more suggestions, but I think the above two books would be a good addition to your library. JMO.
You might want to go to Bobbie Linden's site and read all the good information there. She died about a year ago, but some of her friends keep her site going.
It's Bei-Jei Maltese. One of her last dogs, Tommy, is still showing. He had a Best in Show last weekend or the weekend before.
I love the Vicki Abbott book, she is so specific and its breed specific. I have some other books, but I feel like they just used the same book for every small breed and then slapped a pretty picture on the front.