Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
lam thuc » lam thuoc, am thuc, nam thuc
dinh vi » dinh ve, dinh viet, dinh tri
van lam » van nam
tu sach » thu sach, su sach, te sach
ly hang » ly quang
ly lang » ly vang, le lang, ly lanh
cuu tre » cua tre, cau tren, cau treo

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ly lang) OR (ly hang)) xa hoi. hieu van lam thuc vat ((dinh vi) or (hanh vi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly lang) OR (ly hang)) xa hoi. hieu van lam thuc vat ((dinh vi) OR (hanh vi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly lang) OR (ly hang)) xa hoi. hieu van lam thuc vat ((dinh vi) or (hanh vi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly lang) OR (ly hang)) xa hoi. hieu van lam thuc vat ((dinh vi) or (hanh vi)) cuu tre*.