Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, hieu ve
va thanh » gia thanh, ban thanh, va tinh
nang ma » tang ma, sang ma, nang cao
hieu va » hieu qua
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, xa hoi, ma hoa
du va » dau va, tu va, su va

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

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