Perhaps you should try some spelling variations:
hoc thiet » hoc thieu, hoc thuyet, hoc hien
tao thiet » tai thiet, tay thiet, toan thiet
hanh tran » hanh trang, thanh tran, hanh tram
dung cong » dung trong
tran van » luan van
van dung » van dong, xay dung, tin dung
tac tran » tan tran, tac tren, tac trong
tac trai » tam trai, khac trai, rac thai

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) or (tao thiet)) tach - hanh tran van dung cong ((tac tran) OR (tac trai)) bai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc thiet) OR (tao thiet)) tach - hanh tran van dung cong ((tac tran) OR (tac trai)) bai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc thiet) or (tao thiet)) tach - hanh tran van dung cong ((tac tran) OR (tac trai)) bai".
• Adding a wildcard symbol may retrieve word variants: ((hoc thiet) or (tao thiet)) tach - hanh tran van dung cong ((tac tran) OR (tac trai)) bai*.