@article{VTGU_2015_5_a0,
     author = {M. S. Bukhtyak},
     title = {Normal congruence of paraboloid. {Demiquadrics}},
     journal = {Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mehanika},
     pages = {5--19},
     year = {2015},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VTGU_2015_5_a0/}
}