Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thien van » thi van
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
cac dac » cac dan, cac dai, cac bac
dac ban » cac ban, dac san, duc ban
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang

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