Perhaps you should try some spelling variations:
theo chieu » theo tieu, theo chu, thi chieu
hang nong » thang long, han tong
ho chieu » hoc thieu, doi chieu, mot chieu
thang va » hang va, thong va, thanh va
trang va » tran van, hang va
nong tac » cong tac, dong tac, nong tan
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: ((ho chieu) OR (theo chieu)) xanh - thanh ((thang va) OR (trang va)) hang nong tac toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) or (theo chieu)) xanh - thanh ((thang va) OR (trang va)) hang nong tac toan cao~".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) or (theo chieu)) xanh - thanh ((thang va) OR (trang va)) hang nong tac toan cao*.