Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
cua triet » cua viet, su triet, va triet
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, nam thu, nam tu
thanh do » thanh de, thanh pho, thanh hoa
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, dua tren

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 hoi. hieu van ((nam thuc) or (am thuc)) day thanh do ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu van ((nam thuc) OR (am thuc)) day thanh do ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu van ((nam thuc) or (am thuc)) day thanh do ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu van ((nam thuc) or (am thuc)) day thanh do ((cua tre) OR (cua triet))*.