@article{IVM_1966_6_a14,
     author = {K. Sh. Ramazanova},
     title = {The theory of curvature of $X_2$ in $E_4$},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {137--143},
     year = {1966},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1966_6_a14/}
}