@article{ZNSL_1991_193_a1,
     author = {A. I. Degtyarev},
     title = {Classification of quartics possessing a non-simple singular {point.~II}},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {10--38},
     publisher = {mathdoc},
     volume = {193},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1991_193_a1/}
}