Flatness and projectivity in commutative regular semigroups. S. Bulman-Fleming; K. McDowell — 1980 Semigroup forum
Representation extension properties of normal bands. S. Bulman-Fleming; K. McDowell — 1985 Semigroup forum
A characterization of left cancellative monoids by flatness properties. S. Bulman-Fleming; k. McDowell — 1990 Semigroup forum
Some observations on left absolutely flat monoids. S. Bulman-Fleming; K. McDowell; J. Renshaw — 1990 Semigroup forum