John P. Georges David W. Mauro Melanie I. Stein Labeling Products of Complete Graphs with a Condition at Distance Two. 28-35 2001 14 SIAM J. Discrete Math. 1 http://epubs.siam.org/sam-bin/dbq/article/35185 db/journals/siamdm/siamdm14.html#GeorgesMS01