Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam tu
vai cau » van cau, vai cac, lai chau
toc sac » toc sach, toc san, hoc sach
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
sac ky » cac ky, sai ky
va dan » ca dan, va dao, va dau
va cau » van cau, va cac, 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 sac ky tang xa hoi. hieu va ((nam thuc) or (nam thu)) va dan ((vai cau) OR (va cau)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky tang xa hoi. hieu va ((nam thuc) OR (nam thu)) va dan ((vai cau) OR (va cau)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ky tang xa hoi. hieu va ((nam thuc) or (nam thu)) va dan ((vai cau) OR (va cau)) treo".
• Adding a wildcard symbol may retrieve word variants: toc sac ky tang xa hoi. hieu va ((nam thuc) or (nam thu)) va dan ((vai cau) OR (va cau)) treo*.