Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
bai cua » ban cua, dai cua, bai ca
dao bai » cao bai, dao hai, dao lai
cac toc » cac toi, cac nuoc, cac thoi
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
ma hoi » mai hoi, xa hoi, ma hoa
toc va » hoc va, toc ta, tuc va
va dao » ca dao

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky sang) OR (ky tang)) ma hoi. ((hieu ve) OR (hieu qua)) cac toc va dao bai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky sang) OR (ky tang)) ma hoi. ((hieu ve) or (hieu qua)) cac toc va dao bai cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky sang) OR (ky tang)) ma hoi. ((hieu ve) or (hieu qua)) cac toc va dao bai cua tre*.