Perhaps you should try some spelling variations:
trung cong » truong cong, trong cong, trung uong
hieu quan » hieu qua, lieu quan, thien quan
chu quang » chat quang, vu quang
trung cua » truong cua, trung tuan, dung cua
trung cap » truong cao, trung tam
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan cau » toan cao, toan ban, toan tap

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: ho ((hieu quan) OR (chu quang)) - thanh ((trung cua) OR (trung cap)) trung cong san toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu quan) or (chu quang)) - thanh ((trung cua) OR (trung cap)) trung cong san toan cau~".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu quan) or (chu quang)) - thanh ((trung cua) OR (trung cap)) trung cong san toan cau*.