1. Pullback-Flat Acts are Strongly Flat
2. Flat and strongly flat s-systems
3. Bulman-Fleming, S. The Classification of Monoids by Flatness Properties of Acts. Proceedings of the Conference on Semigroups and Applications. July2–91997, St. Andrews, UK. Edited by: Howie, J. M. and Ruškuc, N. pp.18–38. Singapore: World Scientific.