@article{GDZPPN002077051, title = {k-Tuples of the First n Natural Numbers.}, journal = {Elemente der Mathematik}, volume = {24}, year = {1969}, pages = {133-134}, zbl = {0272.05007}, url = {http://dml.mathdoc.fr/item/GDZPPN002077051} }
Bollobás, Béla. k-Tuples of the First n Natural Numbers.. Elemente der Mathematik, Tome 24 (1969) pp. 133-134. http://gdmltest.u-ga.fr/item/GDZPPN002077051/