Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh vai » thanh hai, thanh van, thanh tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
ve bac » ve bao, ve ban, he bac
ve cac » va cac, vien cac
bo van » vo van, so van, do van

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 ky nang x ho. hieu ((ve bac) or (ve cac)) bo van thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. hieu ((ve bac) OR (ve cac)) bo van thanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. hieu ((ve bac) or (ve cac)) bo van thanh vai cua tre*.