Perhaps you should try some spelling variations:
trinh luan » trinh luat, trinh han, trinh toan
trinh quan » tinh quang, trinh luat, trinh han
dung cong » dung trong
doc hieu » toc thieu, hoc thieu
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan tap » toan ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc hieu) or (hoc hien)) manh - hanh ((trinh luan) OR (trinh quan)) dung cong san toan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc hieu) OR (hoc hien)) manh - hanh ((trinh luan) OR (trinh quan)) dung cong san toan tap.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc hieu) or (hoc hien)) manh - hanh ((trinh luan) OR (trinh quan)) dung cong san toan tap".
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) or (hoc hien)) manh - hanh ((trinh luan) OR (trinh quan)) dung cong san toan tap*.