Perhaps you should try some spelling variations:
theo chieu » theo tieu, ho chieu, theo chu
doi chieu » doc hieu, doi chi, ho chieu
hang cong » hang nong, bang cong, thanh cong
dang cong » dung cong
bai toan » bai tap
toan tap » toan ban
anh son » anh dong, tinh son
son cho » san cho, ton cho, con cho

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 (doi chieu)) xanh - anh son cho ((hang cong) OR (dang cong)) bai toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo chieu) OR (doi chieu)) xanh - anh son cho ((hang cong) OR (dang cong)) bai toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) or (doi chieu)) xanh - anh son cho ((hang cong) OR (dang cong)) bai toan tap".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) or (doi chieu)) xanh - anh son cho ((hang cong) OR (dang cong)) bai toan tap*.