@article{SF_1977__15_134262,
     author = {K.E. Osondu},
     title = {Extensions of homomorphisms of subsemigroups of a group.},
     journal = {Semigroup forum},
     pages = {311--318},
     publisher = {mathdoc},
     volume = {15},
     year = {1977},
     zbl = {0379.20053},
     url = {http://geodesic.mathdoc.fr/item/SF_1977__15_134262/}
}