Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dat hang » dat khanh, dat quang, tat thang
thuc dat » thuc vat, thuc dan, thuc day
nam thuc » nam thuoc, am thuc, nam thu
nang xa » nang x, lang xa, nang ma
hieu he » hieu ve, hiem he, hieu le
so sach » so sanh, bo sach, co sach
he nam » ha nam, nghe nam
di cuu » di cua, dinh cuu
di cau » da cau, diem cau

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 nam thuc dat hang ((di cuu) OR (di cau)) 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 nam thuc dat hang ((di cuu) OR (di cau)) 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 nam thuc dat hang ((di cuu) OR (di cau)) tre*".