@article{GDZPPN002419394,
title = {Perspectivities in Irreducible Collineation Groups of Projective Planes. I.},
journal = {Mathematische Zeitschrift},
volume = {154},
year = {1977},
pages = {95-102},
zbl = {0367.50021},
url = {http://dml.mathdoc.fr/item/GDZPPN002419394}
}
Hering, Christoph; Walker, Michael. Perspectivities in Irreducible Collineation Groups of Projective Planes. I.. Mathematische Zeitschrift, Tome 154 (1977) pp. 95-102. http://gdmltest.u-ga.fr/item/GDZPPN002419394/