@article{05074579,
title = {The Gauss-Bonnet theorem for Cayley-Klein geometries of dimension two.},
journal = {The New York Journal of Mathematics [electronic only]},
volume = {12},
year = {2006},
pages = {143-155},
zbl = {1114.53011},
language = {en},
url = {http://dml.mathdoc.fr/item/05074579}
}
McRae, Alan S. The Gauss-Bonnet theorem for Cayley-Klein geometries of dimension two.. The New York Journal of Mathematics [electronic only], Tome 12 (2006) pp. 143-155. http://gdmltest.u-ga.fr/item/05074579/