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, hieu ve
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cao hoc » co hoc, cho hoc, chat hoc
hoc ban » hoc bang, hoc dan, hoc bai
cua tre » cua te, cuu tre, cua triet

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