Perhaps you should try some spelling variations:
theo chieu » theo tieu, theo chu, thi chieu
nhung cong » dung cong, thong cong, hang cong
tang vatn » tang van, dang van, tan van
ho chieu » hoc thieu, doi chieu, mot chieu
tang vat » tang van, dang vat, bang vat
cong tap » cuong tap, cong tac, cong tan
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap

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 (ho chieu)) xanh - hanh ((tang vat) or (tang vatn)) nhung cong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo chieu) OR (ho chieu)) xanh - hanh ((tang vat) OR (tang vatn)) nhung cong tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) OR (ho chieu)) xanh - hanh ((tang vat) or (tang vatn)) nhung cong tap toan cau".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) OR (ho chieu)) xanh - hanh ((tang vat) or (tang vatn)) nhung cong tap toan cau*.