@article{JMAG_2009_5_a2,
     author = {V. O. Gorkavyy and O. M. Nevmerzhitska},
     title = {Ruled surfaces as pseudospherical congruences},
     journal = {\v{Z}urnal matemati\v{c}eskoj fiziki, analiza, geometrii},
     pages = {359--374},
     publisher = {mathdoc},
     volume = {5},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JMAG_2009_5_a2/}
}