@article{GDZPPN001253018, title = {Spirals of idemopotents from P-semigroups.}, journal = {Semigroup forum}, volume = {18}, year = {1979}, pages = {95-100}, zbl = {0398.20065}, url = {http://dml.mathdoc.fr/item/GDZPPN001253018} }
Byleen, K. Spirals of idemopotents from P-semigroups.. Semigroup forum, Tome 18 (1979) pp. 95-100. http://gdmltest.u-ga.fr/item/GDZPPN001253018/