Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac thuc » cach thuc, cac thu, can thuc
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
qua cac » cua cac
sach ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
danh di » danh du, xanh di, danh dien
hanh de » hanh ve, hanh kem
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 ty ((nang xa) OR (lang xa)) hoi. hieu qua cac thuc va ((danh di) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (lang xa)) hoi. hieu qua cac thuc va ((danh di) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) OR (lang xa)) hoi. hieu qua cac thuc va ((danh di) or (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) OR (lang xa)) hoi. hieu qua cac thuc va ((danh di) or (hanh de)) cua tre*.