@article{SF_1977__15_134255,
     author = {K. Byleen and P. Komj\'ath},
     title = {The admissable trace problem for {E-unitary} inverse semigroups.},
     journal = {Semigroup forum},
     pages = {235--246},
     publisher = {mathdoc},
     volume = {15},
     year = {1977},
     zbl = {0379.20050},
     url = {http://geodesic.mathdoc.fr/item/SF_1977__15_134255/}
}