Perhaps you should try some spelling variations:
thien tinh » thien minh, tien tinh, trien tinh
khien tinh » khien thich, bien tinh, dien tinh
trinh thi » trinh tai, dinh thi, trinh tu
dung cong » dung trong
trinh he » trinh han, trinh hoa, trinh ky
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 tinh) or (khien tinh)) - hanh ((trinh he) OR (trinh thi)) dung cong san toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thien tinh) OR (khien tinh)) - hanh ((trinh he) OR (trinh thi)) dung cong san toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thien tinh) or (khien tinh)) - hanh ((trinh he) OR (trinh thi)) dung cong san toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thien tinh) or (khien tinh)) - hanh ((trinh he) OR (trinh thi)) dung cong san toan cau*.