Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
hang doi » hang di, hang loi, huong doi
dan hang » ban hang, van hang, dat hang
thuc dan » thuc hanh, hoc dan, thuc vat
nang xa » lang xa, nang ma, mang xa
hieu he » hieu ve, hiem he, hieu le
so sach » so sanh, bo sach, co sach
doi cuu » doi cua, doi cuoc
cuu tre » cua tre, cau tren, cau treo
he nam » ha nam, nghe nam

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