Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
nhan duc » nhan duoc, nhan luc, phan duc
su triet » su viet, su tien, ve triet
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
duc van » duc va, duc tan, duc manh
nang ma » tang ma, sang ma, mang may
va nhan » van nhan, ca nhan, va phan

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky ((nang ma) or (nang cao)) hoi. hieu va nhan duc van hanh vi ((va triet) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang ma) OR (nang cao)) hoi. hieu va nhan duc van hanh vi ((va triet) OR (su triet)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang ma) or (nang cao)) hoi. hieu va nhan duc van hanh vi ((va triet) or (su triet))*.