@article{GDZPPN002104245, title = {Schwarz's lemma for circle packings.}, journal = {Inventiones mathematicae}, volume = {88}, year = {1987}, pages = {271-290}, zbl = {0634.30009}, url = {http://dml.mathdoc.fr/item/GDZPPN002104245} }
Rodin, B. Schwarz's lemma for circle packings.. Inventiones mathematicae, Tome 88 (1987) pp. 271-290. http://gdmltest.u-ga.fr/item/GDZPPN002104245/