Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
trong dang » truong dang, trong dong, trong dung
hieu sang » chieu sang, hieu lang, nhieu tang
quang qua » quang cua, quang tuan, quang xuan
trong dan » trong san, trong tan, trong ban
qua dung » quang dung, su dung, qua song
toan ban » van ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) or (hieu quang)) - tinh quang qua dung ((trong dan) OR (trong dang)) toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - tinh quang qua dung ((trong dan) OR (trong dang)) toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu quang)) - tinh quang qua dung ((trong dan) OR (trong dang)) toan ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu quang)) - tinh quang qua dung ((trong dan) OR (trong dang)) toan ban*.