Perhaps you should try some spelling variations:
thanh tung » thanh cong
hanh trinh » canh tranh, hanh chinh
nhung cong » dung cong, thong cong, hang cong
cong thanh » dong thanh, cong trinh, cong tan
hieu sang » chieu sang, hieu lang, hieu quang
cua nhung » va nhung
doc hieu » toc thieu, hoc thieu, hoc hien
phan cau » phan cac, phan tu, phan lap
phan dau » phan tu, hang dau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu sang - ((thanh tung) or (hanh trinh)) cua nhung cong thanh ((phan cau) OR (phan dau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((thanh tung) OR (hanh trinh)) cua nhung cong thanh ((phan cau) OR (phan dau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((thanh tung) or (hanh trinh)) cua nhung cong thanh ((phan cau) OR (phan dau))".
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - ((thanh tung) or (hanh trinh)) cua nhung cong thanh ((phan cau) OR (phan dau))*.