- Reading list (in increasing order of sophistication):
- MR0750661 Cohen, H. ; Lenstra, H. W., Jr. Heuristics on class groups. Number theory (New York, 1982), 26--36, Lecture Notes in Math., 1052, Springer, Berlin, 1984.
- MR0756082 (85j:11144) Cohen, H. ; Lenstra, H. W., Jr. Heuristics on class groups of number fields. Number theory, Noordwijkerhout 1983 (Noordwijkerhout, 1983), 33--62, Lecture Notes in Math., 1068, Springer, Berlin, 1984.
- MR1837670 (2003a:11065) Delaunay, Christophe. Heuristics on Tate-Shafarevitch groups of elliptic curves defined over Q. Experiment. Math. 10 (2001), no. 2, 191--196.
PDFs of these three papers have been placed in my public directory at MSRI, which I think can be accessed by typing cd ~bpoonen/Public at a terminal prompt.