Schützenberger groups of ...-classes in the semigroup of all binary relations on a set. G.B. Preston — 1974 Semigroup forum
Addendum to: Representations of inverse semigroups by one-to-one partial transformations of a set. G.B. Preston — 1974 Semigroup forum
Correction to "Congruences on Brandt Semigroups", Math. Annalen 139, 91?94 (1959). G.B. PRESTON — 1961 Mathematische Annalen
Clifford, A.H. - An appreciation of his his work on the occasion of his sixty-fifth birthday. G.B. Preston — 1974 Semigroup forum