Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hang » van khang, van hoang, van thang
hang dai » hoang dai, hang tai, hang dau
tu sach » thu sach, su sach, te sach
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
x hoi » xa hoi, o hoi, x ho

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) or (toc sach)) ky nang x hoi. hieu qua cac duc van hang dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky nang x hoi. hieu qua cac duc van hang dai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky nang x hoi. hieu qua cac duc van hang dai cua tre*.