@article{GDZPPN002475707,
title = {Extremal Packing and Covering Sets.},
journal = {Monatshefte f\"ur Mathematik},
volume = {71},
year = {1967},
pages = {203-213},
zbl = {0256.52013},
url = {http://dml.mathdoc.fr/item/GDZPPN002475707}
}
Hans, Rajinder Jeet. Extremal Packing and Covering Sets.. Monatshefte für Mathematik, Tome 71 (1967) pp. 203-213. http://gdmltest.u-ga.fr/item/GDZPPN002475707/