Perhaps you should try some spelling variations:
khanh thai » nhanh thai, khanh thanh, khanh thuan
thai cuu » thai cua, tai cuc, thi cuc
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
xuc van » luc van, vuc van, xuc ban
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
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

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 cac ((xuc van) OR (duc van)) khanh thai cuu 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 cac ((xuc van) OR (duc van)) khanh thai 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 ((xuc van) OR (duc van)) khanh thai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (o hai)). hieu ve cac ((xuc van) OR (duc van)) khanh thai cuu tre*.