Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
hieu sang » chieu sang, hieu lang, nhieu tang
nang cong » dang cong, bang cong, hang cong
dan than » dan chan, ban than, van than
than cau » toan cau, phan cau, than cap
tung va » trung va, tuong va, dung va

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 tung va ((nang cong) or (nang song)) dan than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - thanh tung va ((nang cong) OR (nang song)) dan than cau.
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) or (hieu quang)) - thanh tung va ((nang cong) or (nang song)) dan than cau*.