@article{article338cca5f,
title   = {Hyperbolic unit groups and quaternion algebras},
author = {Juriaans, Orlando Stanley and Passi, I. B. S. and Souza Filho, Antônio Calixto de},
year = {2009},
doi = {10.1007/s12044-009-0002-7},
journal   = {Proceedings of the Indian Academy of Sciences - Mathematical Sciences}
}