Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lang van » dang van, tang van, hoang van
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
cac hoc » cach hoc, cac hop, bac hoc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang x) OR (lang van)) hoi. hieu van cac hoc va hanh vi cua tre~.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang x) or (lang van)) hoi. hieu van cac hoc va hanh vi cua tre*.