Perhaps you should try some spelling variations:
hieu cach » hieu cac, chieu sach, hieu ca
canh manh » lanh manh, canh tranh, cach mang
dung cong » dung trong
hoc hieu » hoc thieu, hoc hien, doc hieu
manh vat » manh va, nganh vat, sinh vat
vat dung » van dung, va dung, viet dung
dan than » dan chan, ban than, van than
van tan » van tuan, van ban, van tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu cach - canh manh vat dung cong ((van tan) or (dan than)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cach - canh manh vat dung cong ((van tan) OR (dan than)) tap*.