Perhaps you should try some spelling variations:
cong khanh » cong thanh, cong khan, cong nhan
hieu sang » chieu sang, hieu lang, hieu quang
manh hung » anh huong
manh tung » thanh tung
cua nhung » va nhung
cong hach » cong sach, cong thanh, trong hach
doc hieu » toc thieu, hoc thieu, hoc hien
toan ban » van 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 - ((manh hung) or (manh tung)) cua nhung ((cong hach) OR (cong khanh)) toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - ((manh hung) OR (manh tung)) cua nhung ((cong hach) OR (cong khanh)) toan ban*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu sang - ((manh hung) or (manh tung)) cua nhung ((cong hach) OR (cong khanh)) toan ban*".