@article{MZ_1982__180_173198,
     author = {Thomas Ihringer},
     title = {On {Groupoids} {Having} a {Linear} {Congruence} {Class} {Geometry.}},
     journal = {Mathematische Zeitschrift},
     pages = {395--412},
     year = {1982},
     volume = {180},
     zbl = {0471.51003},
     url = {http://geodesic.mathdoc.fr/item/MZ_1982__180_173198/}
}