Perhaps you should try some spelling variations:
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
dac ban » dac san, duc ban, da ban
cac ban » cac dan, cac van, can ban
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v 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 x ho. ((hieu van) or (thien van)) cac ((dac ban) OR (cac ban)) thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x ho. ((hieu van) OR (thien van)) cac ((dac ban) OR (cac ban)) thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang x ho. ((hieu van) or (thien van)) cac ((dac ban) OR (cac ban)) thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x ho. ((hieu van) or (thien van)) cac ((dac ban) OR (cac ban)) thanh dai cua tre*.