Perhaps you should try some spelling variations:
hai thuc » thai thuc, dai thuc, ha thuc
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
va anh » van anh, va danh, va hanh
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang xa) or (nang ma)) hoi. ((hieu van) or (hieu va)) hai thuc va anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (hieu va)) hai thuc va anh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang xa) or (nang ma)) hoi. ((hieu van) or (hieu va)) hai thuc va anh vi cua tre*.