@article{10_4153_CJM_1987_051_1,
     author = {Jungnickel, Dieter},
     title = {Divisible {Semiplanes,} {Arcs,} and {Relative} {Difference} {Sets}},
     journal = {Canadian journal of mathematics},
     pages = {1001--1024},
     year = {1987},
     volume = {39},
     number = {4},
     doi = {10.4153/CJM-1987-051-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1987-051-1/}
}