There aren't many, but Burney Le Boeuf and Richard Laws' Elephant Seals: Population Ecology, Behavior and Physiology is a classic collection of scientific papers. There's not nearly as much literature on elephant seals as on other marine mammals, so this book is an important one.
I was disappointed to find that it is out of print and all but unavailable. Amazon can connect to a couple of used book dealers who are selling it for over $300.
I have access to copies owned by Friends of the Elephant Seal, but I'd like to acquire my own copy.
The full text is posted online at http://publishing.cdlib.org/ucpressebooks/view?docId=ft7b69p131&brand=ucpress. I still want my own real book.