@article{GDZPPN002061015, title = {Integrability in Codimension 1}, journal = {Commentarii mathematici Helvetici}, volume = {48}, year = {1973}, pages = {195-233}, zbl = {0284.57016}, url = {http://dml.mathdoc.fr/item/GDZPPN002061015} }
Mather, John N. Integrability in Codimension 1. Commentarii mathematici Helvetici, Tome 48 (1973) pp. 195-233. http://gdmltest.u-ga.fr/item/GDZPPN002061015/