Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
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: te ((sach y) or (sach thu)) nang xa hoi. hieu va cac tuc ((van hanh) OR (ban hanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach y) OR (sach thu)) nang xa hoi. hieu va cac tuc ((van hanh) OR (ban hanh)) dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach y) or (sach thu)) nang xa hoi. hieu va cac tuc ((van hanh) OR (ban hanh)) dai cua tre*".