Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
sang tay » sang tao, sang tai, sang tac
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
duc van » duc va, duc tan, duc manh
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
hieu ve » hieu van
tay o » tay co

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: su sach _ sang tay o. ((hieu ve) OR (hieu va)) pham duc van hanh di ((cua triet) OR (va triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach _ sang tay o. ((hieu ve) OR (hieu va)) pham duc van hanh di ((cua triet) or (va triet))~".
• Adding a wildcard symbol may retrieve word variants: su sach _ sang tay o. ((hieu ve) OR (hieu va)) pham duc van hanh di ((cua triet) or (va triet))*.