Perhaps you should try some spelling variations:
thanh trung » thanh tung
chieu sach » chinh sach, chiet tach, chieu sang
nhung cong » dung cong, thong cong, hang cong
hieu tach » hieu cach, chiet tach, lieu thach
hanh tang » hanh trang, anh tang, hanh mang
cong tan » cong tac, cong san, cong thanh
tran cao » toan cao, tran chau, trang cho

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu tach) OR (chieu sach)) - ((hanh tang) or (thanh trung)) va nhung cong tan tran cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu tach) OR (chieu sach)) - ((hanh tang) OR (thanh trung)) va nhung cong tan tran cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu tach) OR (chieu sach)) - ((hanh tang) or (thanh trung)) va nhung cong tan tran cao".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu tach) OR (chieu sach)) - ((hanh tang) or (thanh trung)) va nhung cong tan tran cao*.