@article{JRAM_1972__254_151218,
     author = {Karl Mathiak},
     title = {Homomorphismen projektiver {R\"aume} und {Hjelmslevsche} {Geometrie.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {41--73},
     publisher = {mathdoc},
     volume = {254},
     year = {1972},
     zbl = {0233.50003},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1972__254_151218/}
}