@article{MZ_1978__159_172658,
     author = {Alan Weinstein},
     title = {Bifurcations and {Hamilton's} {Principle.}},
     journal = {Mathematische Zeitschrift},
     pages = {235--248},
     publisher = {mathdoc},
     volume = {159},
     year = {1978},
     zbl = {0366.58003},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__159_172658/}
}