Perhaps you should try some spelling variations:
thuyet tach » thuyet mach, thuyet hach, thuyet xac
hoc thuyet » hoc chuyen
hanh tranh » canh tranh, hanh trinh, hanh trang
nhung cong » thong cong, hang cong, nhung don
tranh cua » doanh cua, manh cua
dung cong » dung trong
dan toan » van toan, dan than, manh toan

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: hoc thuyet tach - hanh tranh cua ((nhung cong) OR (dung cong)) ((dan toan) OR (dan ca)) cau~.
• Adding a wildcard symbol may retrieve word variants: hoc thuyet tach - hanh tranh cua ((nhung cong) or (dung cong)) ((dan toan) or (dan ca)) cau*.