Perhaps you should try some spelling variations:
hieu lang » chieu sang, hieu quang, nhieu tang
dung cong » dung trong
hoc hieu » hoc thieu, hoc hien, doc hieu
anh tang » anh bang, anh dang, anh nang
tang ung » tong ung, dang ung, tang cuong
dan than » dan chan, ban than, van than
van chat » cao chat

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 - anh tang ung dung cong ((dan than) or (van chat)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - anh tang ung dung cong ((dan than) OR (van chat)) ban.
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - anh tang ung dung cong ((dan than) or (van chat)) ban*.