State complexity and the monoid of transformations of a finite set. - Bryan Krawetz; John Lawrence; Jeffrey O. Shallit (Int. J. Found. Comput. Sci., 2005)

Regular Expressions: New Results and Open Problems. - Keith Ellul; Bryan Krawetz; Jeffrey O. Shallit; Ming-wei Wang (J. Autom. Lang. Comb., 2005)