Perhaps you should try some spelling variations:
chieu sang » chieu sach, chieu xanh, nhieu tang
trinh quan » trinh luat, trinh han
luong cong » dung cong, trong cong, cong cong
hieu lang » hieu quang, nhieu tang, hieu van
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 ((chieu sang) or (hieu lang)) - hanh ((trinh quan) OR (tinh quang)) luong cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chieu sang) OR (hieu lang)) - hanh ((trinh quan) OR (tinh quang)) luong cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chieu sang) or (hieu lang)) - hanh ((trinh quan) OR (tinh quang)) luong cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((chieu sang) or (hieu lang)) - hanh ((trinh quan) OR (tinh quang)) luong cong dan toan cau*.