@article{MT_1987_9_a4,
     author = {V. V. Vershinin and V. G. Gorbunov},
     title = {On a quadrangle of spectral sequences},
     journal = {Matemati\v{c}eskie trudy},
     pages = {41--59},
     publisher = {mathdoc},
     volume = {9},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MT_1987_9_a4/}
}