Perhaps you should try some spelling variations:
theo chieu » theo tieu, theo chu, thi chieu
hanh tang » hanh trang, anh tang, hanh mang
va phuong » cac phuong
ho chieu » hoc thieu, doi chieu, mot chieu
dong tac » cong tac, dong tai, dong bac
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.

• Performing a fuzzy search may retrieve terms with similar spellings: ((theo chieu) or (ho chieu)) xanh - hanh tang ((va phuong) OR (va thuong)) dong tac toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo chieu) OR (ho chieu)) xanh - hanh tang ((va phuong) OR (va thuong)) dong tac toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) or (ho chieu)) xanh - hanh tang ((va phuong) OR (va thuong)) dong tac toan cau".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) or (ho chieu)) xanh - hanh tang ((va phuong) OR (va thuong)) dong tac toan cau*.