Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh tai » thanh hai, thanh toan, doanh tai
quoc ban » quoc bao, quoc lan, quoc quan
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, cao hoc, tao hoi
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
ve nam » va nam, le nam, te nam
he nam » ha nam, nghe nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang ((cao hoi) or (co hoi)). hieu ((ve nam) OR (he nam)) quoc ban thanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((cao hoi) OR (co hoi)). hieu ((ve nam) OR (he nam)) quoc ban thanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((cao hoi) or (co hoi)). hieu ((ve nam) OR (he nam)) quoc ban thanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((cao hoi) or (co hoi)). hieu ((ve nam) OR (he nam)) quoc ban thanh tai cua tre*.