Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, thien van, lieu va
sach tu » sach thu, cach tu, sach ty
van hac » van hoc, van ha, van hai
hac duc » hoc duc, ha duc, thach duc
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach tu) or (sach thieu)) hang ((x hoi) OR (x ho)). hieu van hac duc ban thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach tu) OR (sach thieu)) hang ((x hoi) OR (x ho)). hieu van hac duc ban thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach tu) or (sach thieu)) hang ((x hoi) OR (x ho)). hieu van hac duc ban thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach tu) or (sach thieu)) hang ((x hoi) OR (x ho)). hieu van hac duc ban thanh dai cua tre*.