@article{SEMR_2012_9_a17,
     author = {A. A. Khusainov},
     title = {Homology groups of asynchronous systems, {Petri} nets, and trace languages},
     journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a},
     pages = {13--44},
     publisher = {mathdoc},
     volume = {9},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SEMR_2012_9_a17/}
}