Commutative semigroups whose homomorphic images in groups are groups. M.S. Putcha — 1971 Semigroup forum
Viewing results on ...-indecomposable semigroups as solutions to mathematical puzzles. M.S. Putcha — 1974 Semigroup forum
On the maximal semilattice decomposition of the power semigroup of a semigroup. M.S. Putcha Semigroup forum
Application of semigroup algebras to ideal extensions of semigroups. M.S. Putcha; J. Weissglass — 1974 Semigroup forum