Perhaps you should try some spelling variations:
thanh trung » thanh tung
viet sach » viet anh, viet tech
dien sach » dien anh
trung van » truong van, trong van, trung va
dong cong » duong cong, dung cong, dang cong
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than cao » toan cao, thai cao, than cap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((viet sach) or (dien sach)) - thanh trung van dong cong dan than cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((viet sach) OR (dien sach)) - thanh trung van dong cong dan than cao.
• Adding a wildcard symbol may retrieve word variants: hoc ((viet sach) or (dien sach)) - thanh trung van dong cong dan than cao*.