Perhaps you should try some spelling variations:
trinh viet » trinh vat
hieu lang » chieu sang, hieu quang, nhieu tang
ninh viet » sinh vien, anh viet
dung cong » dung trong
cong san » cong tac
san chan » san chang, dan chan, san chay
chan cau » phan cau, can cau, chinh cau
ho hieu » ho chieu, hoi hieu, nho hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu lang - canh ((trinh viet) or (ninh viet)) dung cong san chan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - canh ((trinh viet) OR (ninh viet)) dung cong san chan cau.
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - canh ((trinh viet) or (ninh viet)) dung cong san chan cau*.