@article{GDZPPN002318164,
title = {Hyperbolic Lie Algebras and Quasi-Regular Cusps on Hilbert Modular Surfaces.},
journal = {Mathematische Annalen},
volume = {243},
year = {1979},
pages = {63-88},
zbl = {0396.17007},
url = {http://dml.mathdoc.fr/item/GDZPPN002318164}
}
Lepowsky, James; Moody, Robert V. Hyperbolic Lie Algebras and Quasi-Regular Cusps on Hilbert Modular Surfaces.. Mathematische Annalen, Tome 243 (1979) pp. 63-88. http://gdmltest.u-ga.fr/item/GDZPPN002318164/