@article{MOMA_1992__113_4_178558,
     author = {D.E. Blair and Th. Koufogiorgos},
     title = {Ruled {Surfaces} with {Vanishing} {Second} {Gaussian} {Curvature.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {177--182},
     publisher = {mathdoc},
     volume = {113},
     number = {4},
     year = {1992},
     zbl = {0765.53003},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1992__113_4_178558/}
}