Here's an interesting article from The Guardian: Warren Zevon: the man behind the demons
It was originally published on August 1, 2013 which is why the timeline might seem a bit off.
This article mentions "I'll Sleep When I'm Dead: The Life and Times of Warren Zevon" which is a book written by his ex-wife, Crystal. It is available from Amazon on Kindle and other formats.
We have the paperback version which is nice because you can write in it and it is a large size:
The Warren Zevon Guitar Songbook (Guitar Songbook Edition) Paperback
But it also comes in Kindle, which I might get as well...
The Warren Zevon Guitar Songbook (Guitar Songbook Edition) [Kindle Edition]
Amazon has a "Click to see inside" so you can see the table of contents and an example of the songs. Nice.