Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh vai » hanh vi, hanh va, hanh tai
dang mat » dang vat, dang mau, dung mat
vai cua » dai cua, hai cua, lai cua
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
dang ma » dang mau, dang mam, tang ma
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va

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 ky ((dang ma) or (dang mat)) hoi. hieu van cac ((xuc va) or (luc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((dang ma) OR (dang mat)) hoi. hieu van cac ((xuc va) OR (luc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((dang ma) or (dang mat)) hoi. hieu van cac ((xuc va) or (luc va)) hanh vai cua tre*.