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