@article{10_1017_S0017089500009538,
     author = {Auinger, Karl},
     title = {Bifree objects in e-varieties of strict orthodox semigroups and the lattice of strict orthodox *-semigroup varieties},
     journal = {Glasgow mathematical journal},
     pages = {25--37},
     year = {1993},
     volume = {35},
     number = {1},
     doi = {10.1017/S0017089500009538},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500009538/}
}