Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hang loi » thang loi, hang doi, tang loi
day hang » dat hang, dai hang, day nang
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu le » hieu ve, hieu ly, tieu le
loi cuu » loi cau, loi luu, loai cua
cuu tre » cua tre, cau tren, cau treo
hieu he » hieu ve, hiem he, hieu hien
nang xa » nang x, lang xa, nang ma
so sach » so sanh, bo sach, co sach

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