Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
quoc bao » quoc oai, hoc bao, quoc va
mai khoi » mai khoa, tai khoa, cac khoi
te sach » toc sach
hai cua » thai cua, dai cua, hoi cua
duc ban » duc tan, duc van, dua ban
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet

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 ky dang ((mai hoi) OR (mai khoi)). hieu va chat ((duc ban) or (quoc bao)) thanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang ((mai hoi) OR (mai khoi)). hieu va chat ((duc ban) OR (quoc bao)) thanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky dang ((mai hoi) OR (mai khoi)). hieu va chat ((duc ban) or (quoc bao)) thanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky dang ((mai hoi) OR (mai khoi)). hieu va chat ((duc ban) or (quoc bao)) thanh hai cua tre*.