Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
chieu sang » chieu sach, chieu xanh, hieu lang
hanh tang » hanh trang, anh tang, hanh mang
cong tan » cong tac, cong san, cong thanh
tan toan » tan tran, tap toan, van 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: theo ((hieu nganh) or (chieu sang)) - hanh tang ((cua nhung) OR (va nhung)) cong tan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hieu nganh) OR (chieu sang)) - hanh tang ((cua nhung) OR (va nhung)) cong tan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((hieu nganh) or (chieu sang)) - hanh tang ((cua nhung) OR (va nhung)) cong tan toan cau".
• Adding a wildcard symbol may retrieve word variants: theo ((hieu nganh) or (chieu sang)) - hanh tang ((cua nhung) OR (va nhung)) cong tan toan cau*.