Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh trang » thanh trung, hanh trinh, minh trang
trung cong » truong cong, trong cong, trung uong
hieu lang » chieu sang, nhieu tang, hieu van
cua trung » cua truong, xuan trung, cua nhung
van quang » van quan, tran quang, van tuan
quang cao » nang cao, quang nam
cong van » cong vang, cong san, song van

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (hieu quang)) - ((hanh trang) OR (canh tranh)) cua trung cong van quang cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (hieu quang)) - ((hanh trang) or (canh tranh)) cua trung cong van quang cao~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (hieu quang)) - ((hanh trang) or (canh tranh)) cua trung cong van quang cao*.