@article{GDZPPN001252453, title = {The admissable trace problem for E-unitary inverse semigroups.}, journal = {Semigroup forum}, volume = {14}, year = {1977}, pages = {235-246}, zbl = {0379.20050}, url = {http://dml.mathdoc.fr/item/GDZPPN001252453} }
Byleen, K.; Komjáth, P. The admissable trace problem for E-unitary inverse semigroups.. Semigroup forum, Tome 14 (1977) pp. 235-246. http://gdmltest.u-ga.fr/item/GDZPPN001252453/