Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
pho hai » pho ha
van cac » van hac, van cau, van bac
xuc ban » duc ban, cuc ban, quoc ban
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
y nang » ly nang, v nang, may 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 (ky nang)) pho hai. hieu van cac ((xuc ban) or (duc va)) hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (ky nang)) pho hai. hieu van cac ((xuc ban) OR (duc va)) hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (ky nang)) pho hai. hieu van cac ((xuc ban) or (duc va)) hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) OR (ky nang)) pho hai. hieu van cac ((xuc ban) or (duc va)) hanh tai cua tre*.