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