What about "[book you could buy at bookstore at one point, but not any more]"?
Or, of course, you're making a glib commentary about retail bookstores, in which case, s/bookstore/amazon\.com/g.
Well, anybody can self-publish on Amazon (and I do mean anybody, including the completely illiterate), so I'm not sure that's a very high bar.
It depends on whether the employer will care to check your book references or not, I guess.
What about "[book you could buy at bookstore at one point, but not any more]"?