Perhaps you should try some spelling variations:
khanh thuan » khanh thuong, thanh tuan, khan than
khanh thai » nhanh thai, khanh thanh, thanh hai
thu sach » tu sach, thuat sach, thuoc sach
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
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: thu sach ky nang ((o hoi) or (o hai)). hieu ve cac duc tan ((khanh thai) OR (khanh thuan)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((o hoi) OR (o hai)). hieu ve cac duc tan ((khanh thai) OR (khanh thuan)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((o hoi) or (o hai)). hieu ve cac duc tan ((khanh thai) OR (khanh thuan)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((o hoi) or (o hai)). hieu ve cac duc tan ((khanh thai) OR (khanh thuan)) cua tre*.