Perhaps you should try some spelling variations:
thanh trung » thanh tung
nhung cong » dung cong, thong cong, hang cong
hieu xanh » chieu xanh, hieu manh, hieu nganh
doc hieu » toc thieu, hoc thieu, hoc hien
trung va » truong va, trang va, trung ha
tac toan » tap toan, tam toan, hach toan
tam than » ban than

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 - thanh trung va nhung cong ((tac toan) or (tam than)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu xanh - thanh trung va nhung cong ((tac toan) OR (tam than)) tap.
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - thanh trung va nhung cong ((tac toan) or (tam than)) tap*.