@article{SM_1972_17_4_a7,
     author = {A. I. Vol'pert},
     title = {Differential equations on graphs},
     journal = {Sbornik. Mathematics},
     pages = {571--582},
     year = {1972},
     volume = {17},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1972_17_4_a7/}
}