Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
day hang » dat hang, dai hang, day nang
thuc day » thuc dan, thuc vat
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu he » hieu ve, hiem he, hieu le
so sach » so sanh, bo sach, co sach
hang di » hang doi, hang vi, hang dien
cuu tre » cua tre, cau tren, cau treo
he nam » ha nam, nghe nam
di cuu » di cau, di cua, dinh cuu

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) or (so sach)) ky ((nang xa) OR (lang xa)) hoi. hieu he nam thuc day hang di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (so sach)) ky ((nang xa) OR (lang xa)) hoi. hieu he nam thuc day hang di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (so sach)) ky ((nang xa) OR (lang xa)) hoi. hieu he nam thuc day hang di cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (so sach)) ky ((nang xa) OR (lang xa)) hoi. hieu he nam thuc day hang di cuu tre*.