@article{IM2_1968_2_5_a4,
     author = {D. Ya. Petrina},
     title = {On summation of the contributions from the {Feynman} diagrams. {An}},
     journal = {Izvestiya. Mathematics},
     pages = {1005--1025},
     year = {1968},
     volume = {2},
     number = {5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1968_2_5_a4/}
}