Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
toc sach » hoc sach, doc sach, thuoc sach
van hang » van khang, van hoang, van thang
hang dai » hoang dai, hang tai, hang dau
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
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: ((thu sach) or (toc sach)) ky nang ((o hoi) or (xa hoi)). hieu qua cac duc van hang dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (toc sach)) ky nang ((o hoi) OR (xa hoi)). hieu qua cac duc van hang dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (toc sach)) ky nang ((o hoi) or (xa hoi)). hieu qua cac duc van hang dai cua tre*.