Perhaps you should try some spelling variations:
trang quang » tran quang, trong quang, tranh quang
chieu xanh » chieu sach, chieu sang, chieu tinh
tang quang » dang quang, tang quan, hang quang
hieu lang » chieu sang, hieu quang, nhieu tang
dung cong » dung trong
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cau » toan cao, toan ban, toan tap

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 lang) or (chieu xanh)) - hanh ((trang quang) OR (tang quang)) dung cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (chieu xanh)) - hanh ((trang quang) OR (tang quang)) dung cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) or (chieu xanh)) - hanh ((trang quang) OR (tang quang)) dung cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) or (chieu xanh)) - hanh ((trang quang) OR (tang quang)) dung cong dan toan cau*.