@article{GDZPPN001257722,
title = {Semilattices which must contain a copy of 2 N.},
journal = {Semigroup forum},
volume = {31},
year = {1985},
pages = {71-78},
zbl = {0564.06003},
url = {http://dml.mathdoc.fr/item/GDZPPN001257722}
}
Lawson, J.D.; Mislove, M. Semilattices which must contain a copy of 2 N.. Semigroup forum, Tome 31 (1985) pp. 71-78. http://gdmltest.u-ga.fr/item/GDZPPN001257722/