@article{TRSPY_1991_196_a13,
     author = {K. A. Sitnikov and E. E. Skurikhin},
     title = {Homology on presheaves of sets},
     journal = {Informatics and Automation},
     pages = {156--160},
     publisher = {mathdoc},
     volume = {196},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1991_196_a13/}
}