Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
vai cuu » vai cua
dan vai » dan va, dan tai, dan vat
thuc va » thuc vat, thuc dan, thuc day
cuu tre » cua tre, cau tren, cau treo
hieu va » hieu qua
ky cong » ke cong, ly cong, khu cong
ky long » sy long, ky trong, khi long
ha hoi » hoa hoi, ha noi, xa hoi
va dan » ca dan, va dao, va dau

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 ((ky long) OR (ky cong)) ha hoi. ((hieu va) or (lieu va)) nam thuc va dan vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky long) OR (ky cong)) ha hoi. ((hieu va) OR (lieu va)) nam thuc va dan vai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky long) OR (ky cong)) ha hoi. ((hieu va) or (lieu va)) nam thuc va dan vai cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky long) OR (ky cong)) ha hoi. ((hieu va) or (lieu va)) nam thuc va dan vai cuu tre*.