Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cac thuc » cach thuc, can thuc, cay thuc
hieu va » lieu va, hieu qua
cac thu » cach thuc, cac thoi
va hanh » van hanh, va thanh, va danh
hanh ca » hanh cac, hanh cat, hanh cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ca cua » co cua

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 y nang ((le hoi) or (ma hoa)). hieu va ((cac thuc) OR (cac thu)) va hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((le hoi) OR (ma hoa)). hieu va ((cac thuc) OR (cac thu)) va hanh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((le hoi) or (ma hoa)). hieu va ((cac thuc) OR (cac thu)) va hanh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((le hoi) or (ma hoa)). hieu va ((cac thuc) OR (cac thu)) va hanh ca cua tre*.