Perhaps you should try some spelling variations:
ban hanh » ban hang
so sach » so sanh, co sach, hoc sach
bo sach » co sach, hoc sach
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc ban » thuc ban, truc ban, tu ban
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
di cua » dai cua, doi cua, de cua
o hoi » co hoi, o hoc, o hai

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 (bo sach)) y nang o hoi. hieu va cac tuc ban hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (bo sach)) y nang o hoi. hieu va cac tuc ban hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (bo sach)) y nang o hoi. hieu va cac tuc ban hanh di cua tre*.