Perhaps you should try some spelling variations:
theo chieu » theo tieu, theo chu, thi chieu
hanh trung » thanh trung, hanh trang, manh trung
dap nhung » vap nhung, dap ung, cam nhung
ho chieu » hoc thieu, doi chieu, mot chieu
cong tac » cong ty
tac toan » tap toan, tam toan, hach toan
toan cau » toan cao, toan ban, toan tap

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: ((ho chieu) OR (theo chieu)) xanh - hanh trung ((dap nhung) OR (va nhung)) cong tac toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) or (theo chieu)) xanh - hanh trung ((dap nhung) OR (va nhung)) cong tac toan cau~".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) or (theo chieu)) xanh - hanh trung ((dap nhung) OR (va nhung)) cong tac toan cau*.