Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
truong dao » truong dai, truong cao, truong bo
hieu sang » chieu sang, hieu lang, nhieu tang
truong va » truong dai, truong cao, luong va
nang cong » nang song, dang cong, bang cong
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, 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: doc ((hieu sang) or (hieu quang)) - thanh ((truong va) OR (truong dao)) nang cong dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - thanh ((truong va) OR (truong dao)) nang cong dan than cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) or (hieu quang)) - thanh ((truong va) OR (truong dao)) nang cong dan than cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu quang)) - thanh ((truong va) OR (truong dao)) nang cong dan than cau*.