Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
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 y ((nang xa) OR (lang xa)) hoi. ((hieu ve) or (hieu va)) nam thuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang xa) OR (lang xa)) hoi. ((hieu ve) OR (hieu va)) nam thuc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((nang xa) OR (lang xa)) hoi. ((hieu ve) or (hieu va)) nam thuc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) OR (lang xa)) hoi. ((hieu ve) or (hieu va)) nam thuc va hanh vi cua tre*.