@article{SJIM_2007_10_4_a14,
     author = {A. V. Tropin and S. I. Spivak},
     title = {Approximate analytic integration of the direct kinetic problem},
     journal = {Sibirskij \v{z}urnal industrialʹnoj matematiki},
     pages = {135--148},
     year = {2007},
     volume = {10},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SJIM_2007_10_4_a14/}
}