@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/