Perhaps you should try some spelling variations:
thien tinh » khien tinh, thien minh, tien tinh
hoc thien » hoc hien, hoc thieu, hoc thiet
trang va » tran van, hang va
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
toan tap » toan ban
tang va » tang van, thang va, tang vat

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 - anh ((tang va) or (trang va)) thong ((cong dan) OR (cong san)) toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thien tinh - anh ((tang va) OR (trang va)) thong ((cong dan) OR (cong san)) toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thien tinh - anh ((tang va) or (trang va)) thong ((cong dan) OR (cong san)) toan tap".
• Adding a wildcard symbol may retrieve word variants: hoc thien tinh - anh ((tang va) or (trang va)) thong ((cong dan) OR (cong san)) toan tap*.