Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
va hanh » van hanh, va thanh, ban hanh
tai cua » thai cua, tai cuc, tri cua
va danh » va dinh, va dan, dia danh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
qua hai » qua hoat
tai hai » thi hai, dai hai, tai ha
tai hoi » tai khoi, dai hoi, tai hoe
hai lo » hai ly, hai so, hai le

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((tai hoi) or (tai hai)). hieu qua hai lo ((va hanh) OR (va danh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((tai hoi) OR (tai hai)). hieu qua hai lo ((va hanh) OR (va danh)) tai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((tai hoi) or (tai hai)). hieu qua hai lo ((va hanh) OR (va danh)) tai cua tre*".