Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu cach » chieu sach, hieu ca, biet cach
tang bang » dang bang, tang ban, tang quang
hieu cac » hieu luc, hieu va, hieu van
cong dan » cong san, cong tan, huong dan
dan chan » dan gian, dan ca, van chat
chan cau » phan cau, can cau, chinh cau
tam ban » tai ban, tao ban, tay ban

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cach) OR (hieu cac)) - thanh trung ((tang bang) OR (tam ban)) cong dan chan cau~.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) or (hieu cac)) - thanh trung ((tang bang) or (tam ban)) cong dan chan cau*.