@article{10_1017_S0017089500000240,
     author = {Petrich, Mario},
     title = {Translational hull and semigroups of binary relations},
     journal = {Glasgow mathematical journal},
     pages = {12--21},
     year = {1968},
     volume = {9},
     number = {1},
     doi = {10.1017/S0017089500000240},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500000240/}
}