Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac thuc » cach thuc, cac thu, can thuc
thuc van » thuc vat, thuc dan, thuc va
sach tu » sach thu, cach tu, sach ty
nong xa » song xa, nong va, cong xay
dong xa » dong xay, duong xa, dong ha
hieu va » lieu va, hieu qua
hanh di » hanh de, hang di, danh di
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: toc sach tu ((nong xa) OR (dong xa)) hoi. hieu va cac thuc van ((hanh di) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tu ((nong xa) OR (dong xa)) hoi. hieu va cac thuc van ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tu ((nong xa) OR (dong xa)) hoi. hieu va cac thuc van ((hanh di) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach tu ((nong xa) OR (dong xa)) hoi. hieu va cac thuc van ((hanh di) or (hanh vi)) cua tre*.