Perhaps you should try some spelling variations:
cong thanh » dong thanh, cong trinh, cong tan
hieu xanh » chieu xanh, hieu manh, hieu nganh
doc hieu » toc thieu, hoc thieu, hoc hien
ban cong » bang cong, van cong, phan cong
toan cao » toan ban
toan tap » toan ban
va ban » van ban, va bai, va bao

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 xanh - ((tinh quang) or (canh tranh)) va ban cong thanh ((toan cao) OR (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu xanh - ((tinh quang) OR (canh tranh)) va ban cong thanh ((toan cao) OR (toan tap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - ((tinh quang) or (canh tranh)) va ban cong thanh ((toan cao) OR (toan tap))".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - ((tinh quang) or (canh tranh)) va ban cong thanh ((toan cao) OR (toan tap))*.