Perhaps you should try some spelling variations:
trong van » trong cac
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
tang van » dang van, hoang van, tang luan
hanh vu » hanh vi, hanh va, hanh tu
qua cac » cua cac
so sach » bo sach, co sach, hoc sach
so sanh » do sanh
cac lo » cac lop, cac co, cac bo
lo van » le van, vo van, so van
vu va » vu van, tu va, su 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) or (so sanh)) ty ((tang van) or (trong van)) hoi. hieu qua cac lo van hanh vu va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ty ((tang van) OR (trong van)) hoi. hieu qua cac lo van hanh vu va triet.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) ty ((tang van) or (trong van)) hoi. hieu qua cac lo van hanh vu va triet*.