Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
ty nang » ty xang, ty hang, ly nang
cac bo » bac bo, cac co
bo van » vo van, so van, do van
vi cua » vai cua, di cua
co hai » co dai, co hoi, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ((ty nang) OR (ky nang)) co hai. hieu van cac bo van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ((ty nang) OR (ky nang)) co hai. hieu van cac bo van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ((ty nang) OR (ky nang)) co hai. hieu van cac bo van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ((ty nang) OR (ky nang)) co hai. hieu van cac bo van hanh vi cua tre*.