Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
chat tuc » chat xuc, luat tuc, chat huu
tu sach » thu sach, su sach, te sach
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
nang xa » lang xa, nang ma, mang xa
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 ty ((nang xa) or (nang x)) hoi. hieu va chat tuc ((va thanh) OR (ban thanh)) tri cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (nang x)) hoi. hieu va chat tuc ((va thanh) OR (ban thanh)) tri cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (nang x)) hoi. hieu va chat tuc ((va thanh) OR (ban thanh)) tri cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (nang x)) hoi. hieu va chat tuc ((va thanh) OR (ban thanh)) tri cua tre*.