Dear Gap Forum--I was hoping to do some investigations concerning
SL_2 and PSL_2 of the ring of integers in Q(sqrt(p)). These groups are
finitely presented (I believe) but I haven't been able to find an explicit
presentation in the literature. Specific examples (e.g. p=5) would be of
interest as well as the general case.

Thank you,
Daniel Ruberman

One reference is:

Benjamin Fine,
"Algebraic Theory of the Bianchi Groups"
- Monographs and textbooks in pure and applied mathematics; 129 -
Marcel Dekker, Inc. New York and Basel (1989)

Toni Greil, Muenchen (Germany)
greil@guug.de