Perhaps you should try some spelling variations:
thanh trung » thanh tung
trung hoac » trung hoc, trung hoa, trung ha
hoac khong » hoa khong, hoc khong, hay khong
khong cong » thong cong, khong cang, chong cong
hieu sach » chieu sach, dien sach, hieu cac
hieu cach » hieu cac, chieu sach, hieu ca
dan chan » dan ca, van chat

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 sach) OR (hieu cach)) - thanh trung hoac khong cong ((dan chan) or (dan gian)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sach) OR (hieu cach)) - thanh trung hoac khong cong ((dan chan) OR (dan gian)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sach) OR (hieu cach)) - thanh trung hoac khong cong ((dan chan) or (dan gian)) cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sach) OR (hieu cach)) - thanh trung hoac khong cong ((dan chan) or (dan gian)) cau*.