Perhaps you should try some spelling variations:
phuong cong » phuong dong, phong cong, phung cong
theo chieu » ho chieu, theo chu, thi chieu
va phuong » va thuong, cac phuong
hach toan » thanh toan, manh toan
anh tang » anh bang, anh dang, anh nang
tac toan » tap toan, tam toan, tich toan
tang va » trang va, tang van, thang va

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