@article{VNGU_2006_6_1_a4,
     author = {S. I. Mardaev},
     title = {Graded modal operators and fixed points},
     journal = {Sibirskij \v{z}urnal \v{c}istoj i prikladnoj matematiki},
     pages = {70--76},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VNGU_2006_6_1_a4/}
}