Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
thanh doi » thanh loi, thanh moi, thanh do
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
doi cua » dai cua, hoi cua
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 lang) OR (ky tang)) xa hoi. hieu van nam thuc day thanh doi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky lang) OR (ky tang)) xa hoi. hieu van nam thuc day thanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky lang) OR (ky tang)) xa hoi. hieu van nam thuc day thanh doi cua tre*.