@article{PPN37649882X+dmdlog131, title = {Exkurs \"uber Legendres Parallelentheorie.}, booktitle = {Geometrie Bd. 2}, series = {GDML\_Books}, year = {1968}, pages = {240}, url = {http://dml.mathdoc.fr/item/PPN37649882X+dmdlog131} }
(éd.). Exkurs über Legendres Parallelentheorie., dans Geometrie Bd. 2, GDML_Books, (1968), p. 240. http://gdmltest.u-ga.fr/item/PPN37649882X+dmdlog131/