Perhaps you should try some spelling variations:
hang vai » hang va, hang tai, hang hai
ban hang » ngan hang
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet
ve cao » va cao, ve cac, ve co
y nang » ky nang, ly nang, v nang
ve bao » te bao, va bao
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang ((x hoi) or (o hoi)). hieu ((ve cao) OR (ve bao)) duc ban hang vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (o hoi)). hieu ((ve cao) OR (ve bao)) duc ban hang vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) or (o hoi)). hieu ((ve cao) OR (ve bao)) duc ban hang vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) or (o hoi)). hieu ((ve cao) OR (ve bao)) duc ban hang vai cua tre*.