Perhaps you should try some spelling variations:
thieu quang » thien quan, trien quang, hieu quan
hieu quang » hieu quan, hieu qua, diep quang
nhanh dang » nhan dang, nhanh dong, nhanh lang
duong van » duong va, luong va, dang van
trong van » trong cac
dang va » dang van, dang vat, hang va
va dung » van dung, va duong, vat dung
tan cau » toan cau, van cau, tan ca

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 quang) OR (thieu quang)) - nhanh dang va dung ((duong van) OR (trong van)) tan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu quang) OR (thieu quang)) - nhanh dang va dung ((duong van) or (trong van)) tan cau~".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu quang) OR (thieu quang)) - nhanh dang va dung ((duong van) or (trong van)) tan cau*.