@article{MZM_2011_89_6_a6,
     author = {V. A. Krasnov},
     title = {Real $GM${-Biquadrics}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {868--878},
     publisher = {mathdoc},
     volume = {89},
     number = {6},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2011_89_6_a6/}
}