@article{MAN_1995__301_4_165312,
     author = {Ian M. Anderson and Juha Pohjanpelto},
     title = {Variational principles for differential equations with symmetries and conservation laws. {II.} {Polynomial} differential equations.},
     journal = {Mathematische Annalen},
     pages = {627--654},
     publisher = {mathdoc},
     volume = {301},
     number = {4},
     year = {1995},
     zbl = {0889.58085},
     url = {http://geodesic.mathdoc.fr/item/MAN_1995__301_4_165312/}
}