Noam D. Elkies. Shimura Curves for Level-3 Subgroups of the (2, 3, 7) Triangle Group, and Some Other Examples. In Florian Hess, Sebastian Pauli, Michael E. Pohst, editors, Algorithmic Number Theory, 7th International Symposium, ANTS-VII, Berlin, Germany, July 23-28, 2006, Proceedings. Volume 4076 of Lecture Notes in Computer Science, pages 302-316, Springer, 2006. [doi]
Abstract is missing.