Perhaps you should try some spelling variations:
doi chieu » doc hieu, doi chi, mot chieu
ho chieu » theo chieu, hoc thieu, mot chieu
canh ban » can ban, canh dan, canh van
cua tong » cua dong, cua nong, cua song
cong tac » cong ty
tac toan » tap toan, tam toan, hach toan
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: ((doi chieu) OR (ho chieu)) sang - canh ban ((cua tong) OR (cua cong)) cong tac toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doi chieu) OR (ho chieu)) sang - canh ban ((cua tong) or (cua cong)) cong tac toan cao~".
• Adding a wildcard symbol may retrieve word variants: ((doi chieu) OR (ho chieu)) sang - canh ban ((cua tong) or (cua cong)) cong tac toan cao*.