@article{IM_1980__56_142700,
     author = {Ian Morrison},
     title = {Projective {Stability} of {Ruled} {Surfaces.}},
     journal = {Inventiones mathematicae},
     pages = {269--304},
     year = {1980},
     volume = {56},
     zbl = {0423.14005},
     url = {http://geodesic.mathdoc.fr/item/IM_1980__56_142700/}
}