Perhaps you should try some spelling variations:
hieu cach » hieu cac, chieu sach, hieu ca
tranh qua » tranh cua, thanh qua, trinh qua
dung cong » dung trong
hoc hieu » hoc thieu, hoc hien, doc hieu
qua dung » quang dung, su dung, qua song
van vat » van chat, nhan vat
tan van » tran van, tang van, luan van

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 tranh qua dung cong ((van vat) or (tan van)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cach - canh tranh qua dung cong ((van vat) OR (tan van)) cau.
• Adding a wildcard symbol may retrieve word variants: hoc hieu cach - canh tranh qua dung cong ((van vat) or (tan van)) cau*.