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
luc van » luoc van, luu van, duc van
xuc van » duc van, vuc van, xuc ban
cuu tre » cua tre, cau tren, cau treo
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
co hai » co dai, co hoi, o hai
ve cac » va cac, vien cac
o hoc » co hoc, mo hoc, so hoc

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 hoc) or (co hai)). hieu ve cac ((xuc van) OR (luc van)) khanh thai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoc) OR (co hai)). hieu ve cac ((xuc van) OR (luc van)) khanh thai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoc) or (co hai)). hieu ve cac ((xuc van) OR (luc van)) khanh thai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoc) or (co hai)). hieu ve cac ((xuc van) OR (luc van)) khanh thai cuu tre*.