Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu sach » chieu sach, dien sach, hieu cac
hieu cach » hieu cac, chieu sach, hieu ca
trung cua » truong cua, trung tuan, trung cap
nhung don » nhung van, nhung bo
hang cong » dang cong, hang nong, bang cong
gian nan » gian dan, gian lan, gian van

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