Perhaps you should try some spelling variations:
hanh hang » thanh hang, hang hang, hanh han
dung cong » dung trong
chu sang » thu sang, chieu sang, chuc nang
chu bang » thu bang, chuc nang, chu quang
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap
va dung » van dung, va duong, vat dung

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

• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((chu sang) OR (chu bang)) - hanh hang va dung cong dan toan cao~.
• Adding a wildcard symbol may retrieve word variants: theo ((chu sang) or (chu bang)) - hanh hang va dung cong dan toan cao*.