Perhaps you should try some spelling variations:
ban thanh » ban hang
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
so sach » bo sach, co sach, hoc sach
tai cua » thai cua, tai cuc, tri cua
van cam » van nam, van lam, van cau
cam cuc » cam xuc, cham cuu, pham cuc
xang xa » lang xa, mang xa, ang xa
so sanh » do sanh
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (so sanh)) ty xang xa hoi. hieu van cam cuc ((ban thanh) OR (ban hanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ty xang xa hoi. hieu van cam cuc ((ban thanh) OR (ban hanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (so sanh)) ty xang xa hoi. hieu van cam cuc ((ban thanh) OR (ban hanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) ty xang xa hoi. hieu van cam cuc ((ban thanh) OR (ban hanh)) tai cua tre*.