Perhaps you should try some spelling variations:
thanh trong » thanh trung, tranh trong, hanh trong
trong quang » truong quang, thong quang, trong quan
quang trung » truong trung
hieu quang » thieu quang, hieu quan, hieu qua
chieu sang » chieu sach, chieu xanh, hieu lang
uong dan » huong dan, tuong dan, xuong dan
toan cau » toan cao, toan tap, toan tai
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: hoc ((hieu quang) or (chieu sang)) - thanh trong quang trung uong dan ((toan cau) OR (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu quang) OR (chieu sang)) - thanh trong quang trung uong dan ((toan cau) OR (toan ban)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu quang) or (chieu sang)) - thanh trong quang trung uong dan ((toan cau) OR (toan ban))".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu quang) or (chieu sang)) - thanh trong quang trung uong dan ((toan cau) OR (toan ban))*.