Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
toc sac » toc sach, toc san, hoc sach
vai cua » dai cua, hai cua, lai cua
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ky dang xay hoi. ((hieu va) OR (hieu qua)) nam thuc ((va dan) or (ca dan)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky dang xay hoi. ((hieu va) OR (hieu qua)) nam thuc ((va dan) OR (ca dan)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ky dang xay hoi. ((hieu va) OR (hieu qua)) nam thuc ((va dan) or (ca dan)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sac ky dang xay hoi. ((hieu va) OR (hieu qua)) nam thuc ((va dan) or (ca dan)) vai cua tre*.