@article{AIHPA_1967__7_3_215_0,
     author = {Sen Gupta, N. D.},
     title = {On a perturbation expansion of the characteristic function of classical mechanics},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {215--228},
     publisher = {Gauthier-Villars},
     volume = {7},
     number = {3},
     year = {1967},
     zbl = {0157.55501},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AIHPA_1967__7_3_215_0/}
}