Perhaps you should try some spelling variations:
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
luu ban » luu bang, luu van, luu dan
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
vi cua » vai cua, di cua
ve cam » ve cham, va cam, ve cai
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((o hoi) OR (o hai)). hieu ((ve cam) or (ve cac)) luu ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hai)). hieu ((ve cam) OR (ve cac)) luu ban hanh vi cua 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 cam) or (ve cac)) luu ban hanh vi cua tre*".