Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
vai cau » va cau, van cau, lai chau
vai cac » va cac, tai cac, voi cac
va nam » van 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: toc sach ky lang xa hoi. hieu ((va nam) or (ha nam)) thuc va dan ((vai cau) OR (vai cac)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky lang xa hoi. hieu ((va nam) OR (ha nam)) thuc va dan ((vai cau) OR (vai cac)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky lang xa hoi. hieu ((va nam) or (ha nam)) thuc va dan ((vai cau) OR (vai cac)) treo".
• Adding a wildcard symbol may retrieve word variants: toc sach ky lang xa hoi. hieu ((va nam) or (ha nam)) thuc va dan ((vai cau) OR (vai cac)) treo*.