1. Ang, T., Brzozowski, J.A.: Languages convex with respect to binary relations, and their closure properties. Acta Cybernet. 19(2), 445–464 (2009)
2. Berstel, J., Perrin, D., Reutenauer, C.: Codes and Automata (Encyclopedia of Mathematics and its Applications). Cambridge University Press, New York (2010)
3. Brzozowski, J.A.: Quotient complexity of regular languages. J. Autom. Lang. Comb. 15(1/2), 71–89 (2010)
4. Brzozowski, J.A.: In search of the most complex regular languages. Int. J. Found. Comput. Sci 24(6), 691–708 (2013)
5. Brzozowski, J.A., Davies, S., Liu, B.Y.V.: Most complex regular ideal languages. Discrete Math. Theoret. Comput. Sci. 18(3), 1–25 (2016). Paper #15