@article{DAN_1993_333_4_a13,
     author = {A. A. Shvartsburg},
     title = {Grey solar sail levitation with a non-point light source},
     journal = {Doklady Akademii Nauk},
     pages = {460--464},
     publisher = {mathdoc},
     volume = {333},
     number = {4},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1993_333_4_a13/}
}