Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh ve » hanh vi, hanh va, hanh kem
danh di » danh du, xanh di, danh dien
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet
va am » va lam, va cam
thuc » thu

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 (nang ma)) hoi. hieu va am thuc vat ((danh di) or (hanh ve)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (nang ma)) hoi. hieu va am thuc vat ((danh di) OR (hanh ve)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) OR (nang ma)) hoi. hieu va am thuc vat ((danh di) or (hanh ve)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) OR (nang ma)) hoi. hieu va am thuc vat ((danh di) or (hanh ve)) cua tre*.