@article{IVM_2007_12_a0,
     author = {O. Krupkov\'a and G. E. Prince},
     title = {Lepage forms, closed 2-forms and second-order ordinary differential equations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {3--18},
     publisher = {mathdoc},
     number = {12},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2007_12_a0/}
}