1. On some non-rational congruences on free commutative semigroups;Semigroup Forum;1993-12
2. Cancellative subsemigroups of archimedean semigroups;Semigroup Forum;1980-12
3. Extensions of partially ordered abelian groups;Proceedings of the Japan Academy, Series A, Mathematical Sciences;1980-01-01
4. N-Semigroups and their translation semigroups;Journal of the Australian Mathematical Society;1977-09
5. Abelian groups and $N$-semigroups, II;Proceedings of the Japan Academy, Series A, Mathematical Sciences;1977-01-01