Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
trinh tai » trinh toan, trinh tu, trinh han
trinh he » trinh han, trinh hoa, trinh thi
cong tan » cong tac, cong san, cong thanh
toan cau » toan cao, toan ban, toan tai
toan tap » toan ban
tien » tieng, bien, vien

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toan tien thinh - hanh ((trinh he) OR (trinh tai)) nhung cong tan ((toan cau) OR (toan tap))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toan tien thinh - hanh ((trinh he) or (trinh tai)) nhung cong tan ((toan cau) OR (toan tap))~".
• Adding a wildcard symbol may retrieve word variants: toan tien thinh - hanh ((trinh he) or (trinh tai)) nhung cong tan ((toan cau) OR (toan tap))*.