Hang Zhou Zhiqiu Huang Yi Zhu Polymorphism Sequence Diagrams Test Data Automatic Generation Based on OCL. 1235-1240 2008 ICYCS http://dx.doi.org/10.1109/ICYCS.2008.50 conf/icycs/2008 db/conf/icycs/icycs2008.html#ZhouHZ08