@article{10_4153_CJM_1970_111_1,
     author = {Lallement, G\'erard and Petrich, Mario},
     title = {Extensions of a {Brandt} {Semigroup} by {Another}},
     journal = {Canadian journal of mathematics},
     pages = {974--983},
     year = {1970},
     volume = {22},
     number = {5},
     doi = {10.4153/CJM-1970-111-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1970-111-1/}
}