Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
te sach » toc sach
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach y nang ((ma hoi) OR (xa hoi)). hieu va cac tuc ((va thanh) or (gia thanh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y nang ((ma hoi) OR (xa hoi)). hieu va cac tuc ((va thanh) OR (gia thanh)) hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y nang ((ma hoi) OR (xa hoi)). hieu va cac tuc ((va thanh) or (gia thanh)) hai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach y nang ((ma hoi) OR (xa hoi)). hieu va cac tuc ((va thanh) or (gia thanh)) hai cua tre*.