Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
cu tren » tu tren, dua tren
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
va nam » van nam, ha nam, va nay
do vai » doi vai, do van, do dai
do va » do van, so va

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 dang xa hoi. hieu va nam thuc va ((do vai) or (do va)) ((cau treo) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xa hoi. hieu va nam thuc va ((do vai) OR (do va)) ((cau treo) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xa hoi. hieu va nam thuc va ((do vai) or (do va)) ((cau treo) or (cu tren))*.