@article{GDZPPN000367281, title = {Two Combinatorial Problems in the Plane.}, journal = {Discrete \& computational geometry}, volume = {13}, year = {1995}, pages = {441-444}, zbl = {0826.52009}, url = {http://dml.mathdoc.fr/item/GDZPPN000367281} }
Erdös, P.; Purdy, G. Two Combinatorial Problems in the Plane.. Discrete & computational geometry, Tome 13 (1995) pp. 441-444. http://gdmltest.u-ga.fr/item/GDZPPN000367281/