Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
dung duong » dung dong, dong duong, dung dung
hieu lang » chieu sang, nhieu tang, hieu van
duong anh » duong manh, duong xanh, duong vanh
trinh va » trinh van, trinh vat, trinh vi
trinh ve » trinh he, trinh vi, trinh viet
tuan cau » toan cau, quan cau, tuan cu

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 quang) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) dung duong anh tuan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu quang) OR (hieu lang)) - hanh ((trinh va) OR (trinh ve)) dung duong anh tuan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu quang) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) dung duong anh tuan cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu quang) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) dung duong anh tuan cau*.