Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang xa » lang xa, nang ma, mang xa
va dan » ca dan, va dao, va dau
va cua » va chua, via cua, ca cua
cac co » cac cong

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

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