@article{GDZPPN002095920, title = {Projective Stability of Ruled Surfaces.}, journal = {Inventiones mathematicae}, volume = {56}, year = {1980}, pages = {269-304}, zbl = {0423.14005}, url = {http://dml.mathdoc.fr/item/GDZPPN002095920} }
Morrison, Ian. Projective Stability of Ruled Surfaces.. Inventiones mathematicae, Tome 56 (1980) pp. 269-304. http://gdmltest.u-ga.fr/item/GDZPPN002095920/