REFERENCES
- Howie , J.M. 1976 . An Introduction to Semigroup Theory Academic Press .
- Bulman-Fleming , S. and McDowell , K. 1990 . A Characterizations of Left Cancellative Monoids by Flatness Properties . Semigroup Forum , 40 : 109 – 112 .
- Bulman-Fleming , S. 1992 . Flat and Strongly Flat S-systems . Communications in Algbera , 20 : 2553 – 2567 .
- Bulman-Fleming , S. 1991 . Pullback Flat Acts are Strongly Flat . Canad. Math. Bull. , 34 : 456 – 461 .
- Kilp , M. and Knauer , U. 1986 . On free, Projective and Strongly Flat Acts . Arch. Math. , 47 : 17 – 23 .
- Bulman-Fleming , S. and McDowell , K. 1990 . Monoids over Which all Weakly Flat Acts are Flat . Proc. Edinburgh Math. Soc. , 33 : 287 – 298 .
- Stenström , B. 1971 . Flatness and Localization over Monoids . Math. Nachr. , 48 : 315 – 334 .
- Liu , Z.K. 1994 . Characterization of Monoids by Condition (P) of Cyclic Left Acts . Semigroup Forum , 49 : 31 – 39 .