Perhaps you should try some spelling variations:
ban khanh » ban hanh, ban thanh, van khanh
thai cua » than cua, tai cuc, dai cua
tu sach » thu sach, su sach, te sach
xuc ban » duc ban, cuc ban, quoc ban
cac xuc » cam xuc, cac nuoc, chat xuc
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ve cac » va cac, vien cac
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, 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 hoc)). hieu ve cac xuc ban khanh ((thai cua) or (tri cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac xuc ban khanh ((thai cua) OR (tri cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac xuc ban khanh ((thai cua) or (tri cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) OR (o hoc)). hieu ve cac xuc ban khanh ((thai cua) or (tri cua)) tre*.