@article{FPM_2004_10_4_a9,
     author = {A. E. Pentus and M. R. Pentus},
     title = {Object-oriented representation of hierarchical graphs},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {159--170},
     publisher = {mathdoc},
     volume = {10},
     number = {4},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2004_10_4_a9/}
}