Perhaps you should try some spelling variations:
ban thanh » ban hang
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
van cac » van hac, van cau, van bac
cac dac » cac dan, cac dai, cac bac
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu
x hoi » xa hoi, o hoi, x ho

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