Perhaps you should try some spelling variations:
hanh tranh » canh tranh, hanh trinh, hanh trang
chieu sang » chieu sach, chieu xanh, nhieu tang
hieu lang » hieu quang, nhieu tang, hieu van
tranh cua » doanh cua, manh cua
cong cong » cong dong, dung cong, dang cong
tap toan » tap doan, tap quan, bai toan
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: theo ((hieu lang) or (chieu sang)) - hanh tranh cua ((cong cong) OR (trong cong)) tap toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hieu lang) OR (chieu sang)) - hanh tranh cua ((cong cong) OR (trong cong)) tap toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((hieu lang) or (chieu sang)) - hanh tranh cua ((cong cong) OR (trong cong)) tap toan cao".
• Adding a wildcard symbol may retrieve word variants: theo ((hieu lang) or (chieu sang)) - hanh tranh cua ((cong cong) OR (trong cong)) tap toan cao*.