@article{SIGMA_2012_8_a58,
     author = {Oana Constantinescu},
     title = {Formal integrability for the nonautonomous case of the inverse problem of the calculus of variations},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2012},
     volume = {8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2012_8_a58/}
}