Perhaps you should try some spelling variations:
nhung huong » nhung phuong, nhung tuong, nhung cong
chieu sang » chieu sach, chieu xanh, nhieu tang
huong doan » phuong doan, huong dan, huong loan
hieu lang » hieu quang, nhieu tang, hieu van
trinh vat » trinh van, trinh luat, sinh vat
trinh va » trinh van, trinh ve, trinh vi
doan van » doan va, hoang 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 ((chieu sang) OR (hieu lang)) - canh ((trinh va) or (trinh vat)) nhung huong doan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chieu sang) OR (hieu lang)) - canh ((trinh va) OR (trinh vat)) nhung huong doan van ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chieu sang) OR (hieu lang)) - canh ((trinh va) or (trinh vat)) nhung huong doan van ban".
• Adding a wildcard symbol may retrieve word variants: hoc ((chieu sang) OR (hieu lang)) - canh ((trinh va) or (trinh vat)) nhung huong doan van ban*.