Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
ban thanh » ban hang
ban hanh » ban hang
dang xay » dang van, van xay
hai cua » thai cua, dai cua, hoi cua
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
tang ma » mang may, tang van
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach y ((tang ma) or (dang xay)) hoi. hieu va cac duc ((ban thanh) or (ban hanh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach y ((tang ma) OR (dang xay)) hoi. hieu va cac duc ((ban thanh) OR (ban hanh)) hai cua tre.
• Adding a wildcard symbol may retrieve word variants: thuat sach y ((tang ma) or (dang xay)) hoi. hieu va cac duc ((ban thanh) or (ban hanh)) hai cua tre*.