Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
hieu lang » chieu sang, nhieu tang, hieu van
hang cong » hang nong, bang cong, thanh cong
dang cong » dung cong
tung cao » nung cao, truong cao, trung cap
san phan » san pham, van phan, sat phan
phan cau » phan dau, phan cac, phan tu

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: doi ((hieu lang) OR (hieu quang)) - thanh tung cao ((hang cong) OR (dang cong)) san phan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((hieu lang) or (hieu quang)) - thanh tung cao ((hang cong) OR (dang cong)) san phan cau~".
• Adding a wildcard symbol may retrieve word variants: doi ((hieu lang) or (hieu quang)) - thanh tung cao ((hang cong) OR (dang cong)) san phan cau*.