Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dan thuc » dan toc, am thuc
dinh dai » sinh dai, dinh dao, dinh tai
dinh dat » dinh ket, dinh van, dinh lam
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van dan » van ban, ban dan, van dao
thuc va » thuc vat, thuc dan, thuc day
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: thu ((sach ky) or (cac ky)) nang xa hoi. hieu van dan thuc va ((dinh dai) OR (dinh dat)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (cac ky)) nang xa hoi. hieu van dan thuc va ((dinh dai) OR (dinh dat)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (cac ky)) nang xa hoi. hieu van dan thuc va ((dinh dai) OR (dinh dat)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (cac ky)) nang xa hoi. hieu van dan thuc va ((dinh dai) OR (dinh dat)) cua tre*.