@article{01428675, title = {M\"obius invariants for pairs of spheres }, journal = {Beitr\"age zur Algebra und Geometrie}, volume = {41}, year = {2000}, pages = {233-246}, zbl = {1003.53016}, language = {en}, url = {http://dml.mathdoc.fr/item/01428675} }
Sulanke, Rolf. Möbius invariants for pairs of spheres . Beiträge zur Algebra und Geometrie, Tome 41 (2000) pp. 233-246. http://gdmltest.u-ga.fr/item/01428675/