Natalia Shabaldina Khaled El-Fakih Nina Yevtushenko Testing Nondeterministic Finite State Machines with Respect to the Separability Relation. 305-318 2007 conf/pts/2007 TestCom/FATES http://dx.doi.org/10.1007/978-3-540-73066-8_21 db/conf/pts/testcom2007.html#ShabaldinaEY07