@article{INTG_1969_2_a13,
     author = {N. V. Stepanov},
     title = {Joint invariants of two families of curves on the plane},
     journal = {Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara},
     pages = {299--331},
     publisher = {mathdoc},
     volume = {2},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTG_1969_2_a13/}
}