Weak minimization of DFA - an algorithm and applications. - Bala Ravikumar; Gerry Eisman (Theor. Comput. Sci., 2004)

Approximate Recognition of Non-regular Languages by Finite Automata. - Gerry Eisman; Bala Ravikumar (ACSC, 2005)

On Approximating Non-regular Languages by Regular Languages. - Gerry Eisman; Bala Ravikumar (Fundam. Informaticae, 2011)