Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va danh, ban hanh
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: tu sach y nang ((le hoi) or (ma hoa)). hieu va cac tuc ((va hanh) OR (va thanh)) ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((le hoi) OR (ma hoa)). hieu va cac tuc ((va hanh) OR (va thanh)) ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((le hoi) or (ma hoa)). hieu va cac tuc ((va hanh) OR (va thanh)) ca cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((le hoi) or (ma hoa)). hieu va cac tuc ((va hanh) OR (va thanh)) ca cua tre*.