@article{DAN_1971_197_3_a18,
     author = {K. Ya. Kondrat'ev and A. A. Buznikov and A. G. Nikolaev and V. I. Sevast'yanov and O. I. Smoktiy},
     title = {Results of visual observations of night, twilight and day horizons of the {Earth} from the {``Soyuz-9''} spaceship},
     journal = {Doklady Akademii Nauk},
     pages = {574--577},
     publisher = {mathdoc},
     volume = {197},
     number = {3},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1971_197_3_a18/}
}