M. Ajtai, J. Komlós, and E. Szemerédi. Proceedings of the Fifteenth Annual ACM Symposium on Theory of Computing, page 1--9. New York, NY, USA, ACM, (1983)
D. Bundala, and J. Závodný. Language and Automata Theory and Applications, volume 8370 of Lecture Notes in Computer Science, Springer International Publishing, (2014)