@article{03906763,
title = {Constructions of positive commutative semigroups on the plane. II.},
journal = {International Journal of Mathematics and Mathematical Sciences},
volume = {8},
year = {1985},
pages = {321-324},
doi = {10.1155/S0161171285000333},
zbl = {0568.22003},
language = {en},
url = {http://dml.mathdoc.fr/item/03906763}
}
Farley, Reuben W. Constructions of positive commutative semigroups on the plane. II.. International Journal of Mathematics and Mathematical Sciences, Tome 8 (1985) pp. 321-324. doi : 10.1155/S0161171285000333. http://gdmltest.u-ga.fr/item/03906763/