Perhaps you should try some spelling variations:
trung van » truong van, trong van, trung va
cac trung » cac truong, dac trung, bac trung
van hanh » van thanh, ban hanh, van anh
hanh vai » hanh vi, hanh va, hanh tai
ve triet » va trien, su triet
so sach » so sanh, bo sach, co sach
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
qua cac » cua cac
vai ve » va ve, dai ve, vai va

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 cac trung van hanh vai ve 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 cac trung van hanh vai ve triet.
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang ma) or (sang ma)) hoi. hieu qua cac trung van hanh vai ve triet*.