Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
doan van » doan va, hoang van, luan van
nay thuc » nam thuc, cay thuc, day thuc
cau treo » cau theo, cau tren, cau triet
dong ha » dong hoa, dong va, dong hoc
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, dang xay, lang van
thuc va » thuc vat, thuc dan, thuc day
dan van » dang van, dao van, tan van
va nay » va ngay, va cay

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 ((lang xa) or (dong ha)) hoi. hieu va nay thuc va ((dan van) or (doan van)) cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((lang xa) OR (dong ha)) hoi. hieu va nay thuc va ((dan van) OR (doan van)) cau treo.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((lang xa) or (dong ha)) hoi. hieu va nay thuc va ((dan van) or (doan van)) cau treo*.