@article{MZ_1968__106_171002,
     author = {Radu Rosca},
     title = {On {Isotropic} {Congruences} in {Elliptic} {Space.}},
     journal = {Mathematische Zeitschrift},
     pages = {47--54},
     publisher = {mathdoc},
     volume = {106},
     year = {1968},
     zbl = {0162.53102},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__106_171002/}
}