Perhaps you should try some spelling variations:
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
su sach » so sach, vu sach
va khai » van khai, va khao, va kha
cua tre » cua te, cuu tre, cua triet
sach tu » sach thu, cach tu, sach ty
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
va hai » van hai, va chai, va bai
vi cua » vai cua, di cua

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 hoi. hieu ((va hai) OR (va khai)) truc ((ban hanh) or (van hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu nang xa hoi. hieu ((va hai) OR (va khai)) truc ((ban hanh) OR (van hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tu nang xa hoi. hieu ((va hai) OR (va khai)) truc ((ban hanh) or (van hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach tu nang xa hoi. hieu ((va hai) OR (va khai)) truc ((ban hanh) or (van hanh)) vi cua tre*.