Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
hoc sach » hoc sinh, hoc cac, hoc anh
ty nang » ky nang, ty xang, ty hang
nang co » nang cao, nang doc, nang noi
van cac » van hac, van cau, van bac
cua tre » cuu tre, cua triet, dua tren
co hai » co dai, co hoi, o hai
cac so » cac co, cac bo, cac ho
so van » su van, vo van
cua te » cua tu

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

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