@article{GDZPPN001247832, title = {On extensions onto sub-semigroups of semigroups with two generators.}, journal = {Semigroup forum}, volume = {2}, year = {1971}, pages = {86-88}, zbl = {0237.20061}, url = {http://dml.mathdoc.fr/item/GDZPPN001247832} }
Hedrlin, Z.; Kastl, J. On extensions onto sub-semigroups of semigroups with two generators.. Semigroup forum, Tome 2 (1971) pp. 86-88. http://gdmltest.u-ga.fr/item/GDZPPN001247832/