Goberstein, S. M., & Higgins, P. M. (1987). Semigroups and their applications: Proceedings of the International Conference "Algebraic Theory of Semigroups and Its Applications" held at the California State University, Chico, April 10-12, 1986. D. Reidel ; Sold and distributed in the U.S.A. and Canada by Kluwer Academic.

Goberstein, Simon M.,ed, và Peter M.,ed Higgins. Semigroups and Their Applications: Proceedings of the International Conference "Algebraic Theory of Semigroups and Its Applications" Held at the California State University, Chico, April 10-12, 1986. Dordrecht ; Boston : Norwell, MA, U.S.A.: D. Reidel ; Sold and distributed in the U.S.A. and Canada by Kluwer Academic, 1987.

Goberstein, Simon M.,ed, và Peter M.,ed Higgins. Semigroups and Their Applications: Proceedings of the International Conference "Algebraic Theory of Semigroups and Its Applications" Held at the California State University, Chico, April 10-12, 1986. D. Reidel ; Sold and distributed in the U.S.A. and Canada by Kluwer Academic, 1987.