Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu cua » hieu qua, dieu cua, bieu cua
cho cuu » cho chu, cho cu, cho cua
va hanh » van hanh, va thanh, va danh
cac xuc » cam xuc, cac nuoc, chat xuc
nang co » nang doc, nang noi, nang hoc
cuu tre » cua tre, cau tren, cau treo
sach v » sach va, sach y, sach 2
va dan » ca dan, va dao, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach v ((nang co) OR (nang cao)) hoi. hieu cua cac xuc ((va dan) or (va hanh)) cho cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach v ((nang co) OR (nang cao)) hoi. hieu cua cac xuc ((va dan) OR (va hanh)) cho cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach v ((nang co) OR (nang cao)) hoi. hieu cua cac xuc ((va dan) or (va hanh)) cho cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach v ((nang co) OR (nang cao)) hoi. hieu cua cac xuc ((va dan) or (va hanh)) cho cuu tre*.