Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
tang ma » mang may, tang van
sach ky » sac ky, sach y, sach ty
tang xa » trang xa, lang xa, tang ha
thuc va » thuc vat, thuc dan, thuc day
van tai » von tai, van tuan
tai cau » tai cac, tai cao

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 xa) or (tang ma)) hoi. ((hieu van) OR (lieu va)) nam thuc va van tai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((tang xa) OR (tang ma)) hoi. ((hieu van) OR (lieu va)) nam thuc va van tai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((tang xa) or (tang ma)) hoi. ((hieu van) OR (lieu va)) nam thuc va van tai cau treo".
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((tang xa) or (tang ma)) hoi. ((hieu van) OR (lieu va)) nam thuc va van tai cau treo*.