Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu qua, diep quang
hanh trinh » canh tranh, hanh chinh
hieu quan » hieu qua, lieu quan, thien quan
tong cong » trong cong, cong cong, dung cong
trinh va » trinh van, trinh vat, trinh ve
cong tan » cong tac, cong san, cong thanh
tan than » tan thanh, tan tran, ban than
than cap » khan cap, thanh lap, thanh cac
va tong » va thong, va tuong, va trong

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

• Performing a fuzzy search may retrieve terms with similar spellings: thien ((hieu quang) or (hieu quan)) - hanh trinh va tong cong tan than cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thien ((hieu quang) OR (hieu quan)) - hanh trinh va tong cong tan than cap.
• Adding a wildcard symbol may retrieve word variants: thien ((hieu quang) or (hieu quan)) - hanh trinh va tong cong tan than cap*.