Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
dang cong » dung cong
cong manh » cong danh, duong manh, cong thanh
manh toan » thanh toan, anh tuan, tinh toan
thanh va » thanh van, hanh va, thanh ha
trinh va » trinh van, trinh vat, trinh ve
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: theo ((hieu lang) or (hieu qua)) - hanh ((thanh va) or (trinh va)) dang cong manh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hieu lang) OR (hieu qua)) - hanh ((thanh va) OR (trinh va)) dang cong manh toan cau.
• Adding a wildcard symbol may retrieve word variants: theo ((hieu lang) or (hieu qua)) - hanh ((thanh va) or (trinh va)) dang cong manh toan cau*.