@article{SM_1979_35_2_a6,
     author = {V. T. Fomenko},
     title = {Some properties of two-dimensional surfaces with zero normal torsion in~$E^4$},
     journal = {Sbornik. Mathematics},
     pages = {251--265},
     year = {1979},
     volume = {35},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1979_35_2_a6/}
}