Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
dang xay » dang van, van xay
nam thuc » nam thuoc, am thuc, nam thu
thuc va » thuc vat, thuc dan, thuc day
hieu va » hieu qua
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
cuu tre » cua tre, cau tren, cau treo
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va
va cuu » va cau, va chu, va huu

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) OR (thuoc sach)) ky dang xay hoi. ((hieu va) or (lieu va)) nam thuc va dan va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) ky dang xay hoi. ((hieu va) OR (lieu va)) nam thuc va dan va cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (thuoc sach)) ky dang xay hoi. ((hieu va) or (lieu va)) nam thuc va dan va cuu tre*".