@article{GDZPPN002399199, title = {Closure with Respect to Subplanes.}, journal = {Mathematische Zeitschrift}, volume = {99}, year = {1967}, pages = {57-65}, zbl = {0144.19503}, url = {http://dml.mathdoc.fr/item/GDZPPN002399199} }
Ostrom, T.G. Closure with Respect to Subplanes.. Mathematische Zeitschrift, Tome 99 (1967) pp. 57-65. http://gdmltest.u-ga.fr/item/GDZPPN002399199/