Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach tu » sach thu, cach tu, sach ty
nang xa » lang xa, nang ma, mang xa
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va dinh » van dinh, va kinh, va tinh
ca cua » co cua
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach tu ((nang xa) or (nang x)) hoi. hieu va cac duc ((va dinh) or (van hanh)) ca cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu ((nang xa) OR (nang x)) hoi. hieu va cac duc ((va dinh) OR (van hanh)) ca cua te.
• Adding a wildcard symbol may retrieve word variants: su sach tu ((nang xa) or (nang x)) hoi. hieu va cac duc ((va dinh) or (van hanh)) ca cua te*.