I have access to an _awful_ lot of books through my library's interlibrary loan network. Of books that I wanted to get because they were relevant to something in Wikipedia that I was working on, I've probably been able to get three out of four. Not fantastically obscure books, but not exactly Barnes and Noble fodder, either. Specific examples (all long out of print): Abram Sachar's "Brandeis University: A Host at Last" (his 1995 history of Brandeis); Elsie de Wolfe's autobiography, _After All_; de Seversky's "Victory Through Air Power" (the 1942 book, not the Disney version!); B. Traven's novel, "The Death Ship." Actually if my library can't get it through the Minuteman network, they can get it from the Boston Public Library, the Commonwealth's "library of last resort." The Boston Public Library has fourteen million volumes which makes it bigger than Yale's and only a tad smaller than Harvard's. They've done this for me twice. I don't know exactly what resources other Wikipedians have, but interlibrary loan networks are not unique to my region of the U. S. I'm not sure how I could get the wall of College Hall, University of Pennsylvania sent to me by interlibrary loan. Reference librarians are very accommodating, but I don't think I could ask the Penn reference librarian to go there and take a snapshot of it for me. (Although you never know, and I admit that I haven't actually tried).