@article{GDZPPN002296357, title = {\"Uber konservative Transformationen.}, journal = {Mathematische Annalen}, volume = {163}, year = {1966}, pages = {44-61}, url = {http://dml.mathdoc.fr/item/GDZPPN002296357} }
HELMBERG, G. Über konservative Transformationen.. Mathematische Annalen, Tome 163 (1966) pp. 44-61. http://gdmltest.u-ga.fr/item/GDZPPN002296357/