@article{MZ_1978__161_172699,
     author = {Ronald A. Knight},
     title = {Prolongationally {Stable} {Transformation} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {189--194},
     year = {1978},
     volume = {161},
     zbl = {0365.57017},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__161_172699/}
}