@article{10_4171_dm_206,
     author = {Ernst-Ulrich Gekeler},
     title = {The distribution of group structures on elliptic curves over finite prime fields},
     journal = {Documenta mathematica},
     pages = {119--142},
     year = {2006},
     volume = {11},
     doi = {10.4171/dm/206},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/206/}
}