Perhaps you should try some spelling variations:
thien danh » thien anh, thien dang, thien thanh
hieu manh » chieu xanh, hieu nganh, dieu hanh
trinh chu » trinh cau, trinh thuc, trinh chat
trinh cho » trinh chao, trinh co, trinh chat
bang cong » dang cong, bang song, hang cong
cong san » cong tac
san toan » van toan, dan toan, manh 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: hoc ((thien danh) or (hieu manh)) - canh ((trinh chu) OR (trinh cho)) bang cong san toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thien danh) OR (hieu manh)) - canh ((trinh chu) OR (trinh cho)) bang cong san toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thien danh) or (hieu manh)) - canh ((trinh chu) OR (trinh cho)) bang cong san toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thien danh) or (hieu manh)) - canh ((trinh chu) OR (trinh cho)) bang cong san toan cau*.