Perhaps you should try some spelling variations:
thanh tung » thanh cong
hanh trinh » canh tranh, hanh chinh
cong thanh » dong thanh, cong tan, truong thanh
hieu lang » chieu sang, hieu quang, nhieu tang
cua thong » cua thuong, cua khong, cua tong
toan cao » toan ban, toan tap
ho hieu » ho chieu, hoi hieu, nho hieu

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

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