Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
va danh » va dinh, va hanh, dia danh
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
me hoi » le hoi
va dan » ca dan, va dao, va dau
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 ((me hoi) or (ma hoa)). hieu va cac tac ((va danh) OR (va dan)) ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang ((me hoi) OR (ma hoa)). hieu va cac tac ((va danh) OR (va dan)) ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((me hoi) or (ma hoa)). hieu va cac tac ((va danh) OR (va dan)) ca cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((me hoi) or (ma hoa)). hieu va cac tac ((va danh) OR (va dan)) ca cua tre*.