@article{AM2_1981__22_136868,
     author = {Klaus Vedder and Henda Swart},
     title = {Subplane replacement in projective planes.},
     journal = {Aequationes mathematicae},
     pages = {134--139},
     publisher = {mathdoc},
     volume = {22},
     year = {1981},
     zbl = {0481.51009},
     url = {http://geodesic.mathdoc.fr/item/AM2_1981__22_136868/}
}