Perhaps you should try some spelling variations:
dat thanh » dao thanh, dat khanh, dang thanh
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
thuc dat » thuc vat, thuc dan, thuc day
cau thuc » cau truc, cuu thuc, can thuc
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach kem
tang xa » trang xa, tang ma, lang xa
sach ty » sach y, sach tu, sach thu

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: su ((sach ky) OR (sach ty)) tang xa hoi. hieu van cau thuc dat thanh va ((cua tre) OR (cua vat))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) tang xa hoi. hieu van cau thuc dat thanh va ((cua tre) or (cua vat))~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) tang xa hoi. hieu van cau thuc dat thanh va ((cua tre) or (cua vat))*.