@article{DAN_1967_172_5_a17,
     author = {V. B. Tulvinskii and Yu. A. Shuba},
     title = {On the relative role of direct and indirect transitions in optical absorption},
     journal = {Doklady Akademii Nauk},
     pages = {1057--1058},
     publisher = {mathdoc},
     volume = {172},
     number = {5},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_172_5_a17/}
}