Perhaps you should try some spelling variations:
khanh thai » nhanh thai, khanh thanh, khanh thuan
van khanh » van thanh, van hanh, van anh
thai cau » thai cao, toan cau, thai van
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
so hai » son hai, su hai, so ha
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hai

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 (so hai)). hieu ve cac luc van khanh thai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (so hai)). hieu ve cac luc van khanh thai cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (so hai)). hieu ve cac luc van khanh thai cau tren*.