@inproceedingsPlace_van Rooijen_Zeitoun_2013, place=Berlin, Heidelberg, title=Separating Regular Languages by Piecewise Testable and Unambiguous Languages, DOI=10.1007/978-3-642-40313-2_64, booktitle=Mathematical Foundations of Computer Science 2013 - 38th International Symposium, (MFCS) 2013, Klosterneuburg, Austria, August 26-30, 2013, publisher=Springer Berlin Heidelberg, author=Place, Thomas and van Rooijen, Lorijn and Zeitoun, Marc, year=2013, pages=729–740