Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
buoc ban » buon ban, duoc ban, thuoc ban
quoc ban » quoc bao, quoc lan, quoc quan
thanh te » thanh ve, thanh de, thanh le
te sach » toc sach
hieu te » hieu ve, hien te, hieu he
cua tre » cua te, cuu tre, cua triet
te cua » tue cua, le cua, de cua
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: ((te sach) or (hoc sach)) ky nang x hoi. hieu te hoc ((buoc ban) OR (quoc ban)) thanh te cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (hoc sach)) ky nang x hoi. hieu te hoc ((buoc ban) OR (quoc ban)) thanh te cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (hoc sach)) ky nang x hoi. hieu te hoc ((buoc ban) OR (quoc ban)) thanh te cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (hoc sach)) ky nang x hoi. hieu te hoc ((buoc ban) OR (quoc ban)) thanh te cua tre*.