@article{02033360, title = {Helmholtz type condition for mechanical integrators.}, journal = {Novi Sad Journal of Mathematics}, volume = {29}, year = {1999}, pages = {11-21}, zbl = {1029.37502}, language = {en}, url = {http://dml.mathdoc.fr/item/02033360} }
Albu, Ion D.; Opris, Dumitru. Helmholtz type condition for mechanical integrators.. Novi Sad Journal of Mathematics, Tome 29 (1999) pp. 11-21. http://gdmltest.u-ga.fr/item/02033360/