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