Perhaps you should try some spelling variations:
nay thuc » nam thuc, cay thuc, day thuc
toc sac » toc sach, toc san, hoc sach
ca tren » cau tren, cu tren, la tren
dao vai » dao van, dao va, dao bai
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
van hoi » van hoa, van hoc, van hoe
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
va dao » ca dao
va nay » va ngay, va cay

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 lang) OR (ky dang)) van hoi. hieu va nay thuc va dao vai ((ca tren) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ((ky lang) OR (ky dang)) van hoi. hieu va nay thuc va dao vai ((ca tren) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ((ky lang) OR (ky dang)) van hoi. hieu va nay thuc va dao vai ((ca tren) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: toc sac ((ky lang) OR (ky dang)) van hoi. hieu va nay thuc va dao vai ((ca tren) or (cua tre))*.