Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
canh trang » canh tranh, hanh trang, banh trang
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, nhieu tang, hieu van
trang va » tran van, hang va
van toan » van tan, van thanh, manh toan
van tuan » van quan, van ban, anh tuan

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu lang) OR (hieu quang)) - canh trang va nhung cong ((van toan) or (van tuan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (hieu quang)) - canh trang va nhung cong ((van toan) OR (van tuan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) OR (hieu quang)) - canh trang va nhung cong ((van toan) or (van tuan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) OR (hieu quang)) - canh trang va nhung cong ((van toan) or (van tuan)) cau*.