What is the shortest Ph.D. thesis?
David Rector's thesis ("An Unstable Adams Spectral Sequence", MIT 1966) is 9 pages, according to the record at the MIT library. I haven't seen the actual thesis for many years, but I'm pretty the actual mathematical content takes about 3 pages total, and is largely identical to the published version in Topology (1966, same title), which is 3 pages plus bibliography. (Dan Kan, his advisor, likes short papers.)
John Nash's thesis was 26 pages, and had two references in the bibliography.
Edmund Landau's thesis was 13 pages long.