Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
tai cua » thai cua, tai cuc, tri cua
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
nang ma » tang ma, sang ma, nang cao
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: thuoc sach ky ((mang may) or (nang ma)) hoi. hieu van cac ((xuc va) or (luc va)) doanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky ((mang may) OR (nang ma)) hoi. hieu van cac ((xuc va) OR (luc va)) doanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky ((mang may) or (nang ma)) hoi. hieu van cac ((xuc va) or (luc va)) doanh tai cua tre*.