Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
thuc day » thuc vat
thuc dan » thuc hanh, hoc dan, thuc vat
danh dai » danh dau, danh di, danh sai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet

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: tu sach ky nang xa hoi. ((hieu van) OR (lieu va)) chat ((thuc day) OR (thuc dan)) danh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. ((hieu van) OR (lieu va)) chat ((thuc day) or (thuc dan)) danh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. ((hieu van) OR (lieu va)) chat ((thuc day) or (thuc dan)) danh dai cua tre*.