Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
dang xay » dang van, van xay
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » hieu qua
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
thuc va » thuc vat, thuc dan, thuc day
cuu tre » cua tre, cau tren
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 dang xay hoi. ((hieu va) or (lieu va)) nam thuc va dan ca ((cuu tre) OR (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xay hoi. ((hieu va) OR (lieu va)) nam thuc va dan ca ((cuu tre) OR (cau treo))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang xay hoi. ((hieu va) or (lieu va)) nam thuc va dan ca ((cuu tre) OR (cau treo))*".