Robert Ash, a mathematics professor from the University of Illinois at Urbana-Champaign, offers two graduate level textbooks on his homepage. The first is an introduction to abstract algebra. Roughly 400 pages in length, the book is divided into individual chapters so readers can download only what interests them. The second book, which was released in 2003, covers algebraic number theory. While significantly shorter, it incorporates many of the principles introduced in the abstract algebra book. Solutions to the sample questions scattered throughout each book are given in appendices.