Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu manh » chieu xanh, hieu nganh, dieu hanh
manh toan » thanh toan, anh tuan, tinh toan
hoc hieu » hoc thieu, hoc hien, doc hieu
tac toan » tap toan, tam toan, hach toan
va hanh » van hanh, va thanh, va danh
va lang » va nang, hoa lang

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: hoc hieu manh - thanh trung ((va hanh) OR (va lang)) cong ((tac toan) OR (manh toan)) tap~.
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - thanh trung ((va hanh) or (va lang)) cong ((tac toan) or (manh toan)) tap*.