Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cuu san » cuu van, cua san, cuu ban
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
ve cac » va cac, vien cac
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa
d cuu » _ cuu

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 nang ((o hoi) OR (o hai)). hieu ve cac ((cua ban) OR (cuu san)) anh d cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) OR (o hai)). hieu ve cac ((cua ban) or (cuu san)) anh d cuu tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) OR (o hai)). hieu ve cac ((cua ban) or (cuu san)) anh d cuu tre*.