@article{GDZPPN002308010, title = {A Ramsey-Type Problem for Paths in Digraphs.}, journal = {Mathematische Annalen}, volume = {201}, year = {1973}, pages = {117-118}, zbl = {0239.05119}, url = {http://dml.mathdoc.fr/item/GDZPPN002308010} }
Williamson, James E. A Ramsey-Type Problem for Paths in Digraphs.. Mathematische Annalen, Tome 201 (1973) pp. 117-118. http://gdmltest.u-ga.fr/item/GDZPPN002308010/