@article{ZNSL_2013_418_a5,
     author = {E. G. Emel'yanov},
     title = {The tangent properties of trajectories of certain two quadratic differentials},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {90--104},
     publisher = {mathdoc},
     volume = {418},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2013_418_a5/}
}