There are no books that are devoted entirely to V. salvadorii, but there are some books that have species accounts, and speak about whatever information is available about them... Unfortunately, most of what is known about Crocodile Monitors comes from captive observations and studies. Very little is known about them in the wild.
I would suggest Pianka and King's new book, Varanoid Lizards of the World, as well as Daniel Bennet's book of Monitor Lizards. Both of these books have good species accounts... probably the best you will be able to find. I hope this helps a bit, cheers, have a great day!
Bob
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