@article{MZ_1970__116_171374,
     author = {Robert A. Liebler},
     title = {Finite {Affine} {Planes} of {Rank} {Three} are {Translation} {Planes.}},
     journal = {Mathematische Zeitschrift},
     pages = {89--93},
     year = {1970},
     volume = {116},
     zbl = {0197.16802},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__116_171374/}
}