Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
nhanh tinh » nhanh thanh, hanh trinh, nhan sinh
hieu lang » chieu sang, nhieu tang, hieu van
hanh tinh » hanh trinh, thanh tinh, canh tinh
dung cong » dung trong
cua dung » cua dang, cua dong, qua dung
cong san » cong tac
san than » sang than, san thanh, ban than
than cao » toan cao, thai cao, than cap

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

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