Maria Bustillos in The Awl:
Among David Foster Wallace's papers at the Ransom Center at the University of Texas at Austin are three hundred-odd books from his personal library, most of them annotated, some heavily as if he were scribbling a dialogue with the author page by page. There are several of his undergraduate papers from Amherst; drafts of his fiction and non-fiction; research materials; syllabi; notes, tests and quizzes from classes he took, and from those he taught; fan correspondence and juvenilia. As others have found, it's entirely boggling for a longtime fan to read these things. I recently spent three days in there and have yet to cram my eyeballs all the way back in where they belong.
Wallace committed suicide in 2008. There has been a natural reluctance to broach questions surrounding the tragedy with his family and friends, just as there was reluctance to ask him directly about his personal history when he was alive. But there are indications—particularly in the markings of his books—of Wallace's own ideas about the sources of his depression, some of which seem as though they ought to be the privileged communications of a priest or a psychiatrist. But these things are in a public archive and are therefore going to be discussed and so I will tell you about them.
One surprise was the number of popular self-help books in the collection, and the care and attention with which he read and reread them. I mean stuff of the best-sellingest, Oprah-level cheesiness and la-la reputation was to be found in Wallace's library. Along with all the Wittgenstein, Husserl and Borges, he read John Bradshaw, Willard Beecher, Neil Fiore, Andrew Weil, M. Scott Peck and Alice Miller. Carefully.