1. Bulman-Fleming, S., Nasir, S.: Examples concerning absolute flatness and amalgamation in pomonoids. Semigroup Forum 80, 272–292 (2010)
2. Howie, J.M.: Fundamentals of Semigroup Theory. Clarendon Press, Oxford (1995)
3. Kiss, E.W., Márki, L., Pröhle, P., Tholen, W.: Categorical algebraic properties. A compendium on amalgamation, congruence extension, epimorphisms, residual smallness, and injectivity. Studia Sci. Math. Hungar. 18, 79–141 (1983)
4. Laan, V., Nasir, S.: On mono- and epimorphisms in varieties of ordered algebras. Commun. Algebr. (accepted)
5. Nasir, S.: Absolute flatness and amalgamation in pomonoids. Semigroup Forum 82, 504–515 (2011)