@article{CMUC_1989_30_1_a19,
     author = {Tzouvaras, Athanossios},
     title = {Simple motions},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {163--173},
     year = {1989},
     volume = {30},
     number = {1},
     mrnumber = {995715},
     zbl = {0671.03034},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1989_30_1_a19/}
}