Perhaps you should try some spelling variations:
hieu sang » chieu sang, hieu lang, hieu quang
cong hoat » cong hoa, rong hoat, cong hoan
hoat dung » hoat dong, hat dung, hoang dung
dung cong » dung trong
doc hieu » toc thieu, hoc thieu, hoc hien
cong tac » cong ty
tac tran » tan tran, tac trai, tac tren
tran ban » tranh ban, tran van, toan ban

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 - thanh cong hoat dung cong tac tran ban~.
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - thanh cong hoat dung cong tac tran ban*.