Perhaps you should try some spelling variations:
theo chieu » theo tieu, ho chieu, theo chu
thanh dung » thanh duong, thanh tung, thanh hung
mot chieu » doi chieu, ho chieu
dong cong » duong cong, dung cong, dang cong
dung cua » dung luan, dung cho
cua dong » chua dong, cua cong, cua dang
tap toan » tap quan, bai toan
tap doan » tap quan

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 (mot chieu)) xanh - thanh dung cua dong cong ((tap toan) OR (tap doan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) or (mot chieu)) xanh - thanh dung cua dong cong ((tap toan) OR (tap doan)) cau~".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) or (mot chieu)) xanh - thanh dung cua dong cong ((tap toan) OR (tap doan)) cau*.