Perhaps you should try some spelling variations:
thiet thanh » thien thanh, thi thanh, them thanh
viet thanh » viet anh
nhung cong » dung cong, thong cong, hang cong
trung ha » trung hoc, trung tam, trung cap
trang va » tran van, hang va
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
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 ((thiet thanh) OR (viet thanh)) - thanh ((trung ha) or (trang va)) nhung cong dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet thanh) OR (viet thanh)) - thanh ((trung ha) OR (trang va)) nhung cong dan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet thanh) OR (viet thanh)) - thanh ((trung ha) or (trang va)) nhung cong dan toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet thanh) OR (viet thanh)) - thanh ((trung ha) or (trang va)) nhung cong dan toan cao*.