Perhaps you should try some spelling variations:
thieu xanh » chieu xanh, thien anh, thien danh
hieu manh » chieu xanh, hieu nganh, dieu hanh
hang hang » nang hang, cang thang, hung thang
cong tap » cuong tap, cong tac, cong tan
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap
ca hang » cua hang, ca chang, ca tang
va hang » van hang, va nang, va lang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thieu xanh) or (hieu manh)) - hang hang ((ca hang) OR (va hang)) cong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu xanh) OR (hieu manh)) - hang hang ((ca hang) OR (va hang)) cong tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu xanh) or (hieu manh)) - hang hang ((ca hang) OR (va hang)) cong tap toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu xanh) or (hieu manh)) - hang hang ((ca hang) OR (va hang)) cong tap toan cau*.