Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
thieu sach » chieu sach, thien hach, theo sach
hieu cach » hieu cac, chieu sach, hieu ca
canh manh » lanh manh, canh tranh, cach mang
van toan » van tuan, van tan, van thanh
dan than » dan chan, ban than, van than
manh va » hanh va, anh va, minh va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu sach) OR (hieu cach)) - canh manh va nhung cong ((van toan) or (dan than)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (hieu cach)) - canh manh va nhung cong ((van toan) OR (dan than)) tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) OR (hieu cach)) - canh manh va nhung cong ((van toan) or (dan than)) tap".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) OR (hieu cach)) - canh manh va nhung cong ((van toan) or (dan than)) tap*.