@article{RM_1983_38_2_a1,
     author = {V. I. Arnol'd},
     title = {Singularities of systems of rays},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {87--176},
     publisher = {mathdoc},
     volume = {38},
     number = {2},
     year = {1983},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1983_38_2_a1/}
}