Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach
thuat tach » thuat sach, thuat mach, thuat tac
hanh tran » hanh trang, thanh tran, hanh tram
dung cong » dung trong
manh toan » thanh toan, anh tuan, tinh toan
tran van » luan van
van dung » van dong, xay dung, tin dung
dan toan » van toan, dan than, xuan toan

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