Synthesis and Selective Cytotoxic Activities on Rhabdomyosarcoma and Noncancerous Cells of Some Heterocyclic Chalcones oleh Tuong-Ha Do, Dai-Minh Nguyen, Van-Dat Truong, Thi-Hong-Tuoi Do, Minh-Tri Le, Thanh-Quan Pham, Khac-Minh Thai, Thanh-Dao Tran