TY  - JOUR
AU  - T.E. Nordahl
TI  - Commutative semigroups whose proper subsemigroups are projective.
JO  - Semigroup forum
PY  - 1974
SP  - 35
EP  - 41
VL  - 6
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SF_1974__6_133957/
ID  - SF_1974__6_133957
ER  -