Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
nam trung » nam trong, tai trung, ba trung
cam trung » cam truong, cac trung, cao trung
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang ma) OR (sang ma)) hoi. hieu qua ((cam trung) or (nam trung)) van hanh vi cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang ma) OR (sang ma)) hoi. hieu qua ((cam trung) OR (nam trung)) van hanh vi cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang ma) OR (sang ma)) hoi. hieu qua ((cam trung) or (nam trung)) van hanh vi cua triet".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang ma) OR (sang ma)) hoi. hieu qua ((cam trung) or (nam trung)) van hanh vi cua triet*.