@article{GDZPPN002318571, title = {Perfect Elements in the Free Modular Lattices.}, journal = {Mathematische Annalen}, volume = {250}, year = {1980}, pages = {95-100}, zbl = {0443.06005}, url = {http://dml.mathdoc.fr/item/GDZPPN002318571} }
Dlab, Vlastimil; Ringel, Claus Michael. Perfect Elements in the Free Modular Lattices.. Mathematische Annalen, Tome 250 (1980) pp. 95-100. http://gdmltest.u-ga.fr/item/GDZPPN002318571/