@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/