@article{1183495753, author = {Cummings, Louise D.}, title = {Hexagonal systems of seven lines in a plane}, journal = {Bull. Amer. Math. Soc.}, volume = {38}, number = {12}, year = {1932}, pages = { 105-110}, language = {en}, url = {http://dml.mathdoc.fr/item/1183495753} }
Cummings, Louise D. Hexagonal systems of seven lines in a plane. Bull. Amer. Math. Soc., Tome 38 (1932) no. 12, pp. 105-110. http://gdmltest.u-ga.fr/item/1183495753/