Perhaps you should try some spelling variations:
thanh hoi » thanh hoai, thanh hoa, thanh hai
day thanh » dao thanh, dat thanh, da thanh
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, nam thu, nam tu
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hoi cua » hoi chuc
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: toc sach ky ((nang xa) OR (lang xa)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang xa) OR (lang xa)) hoi. hieu van ((nam thuc) OR (am thuc)) day thanh hoi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((nang xa) OR (lang xa)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh hoi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang xa) OR (lang xa)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh hoi cua tre*.