Perhaps you should try some spelling variations:
khanh thai » nhanh thai, khanh thanh, khanh thuan
van khanh » van thanh, van hanh, van anh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
thai ca » thai cua, thai cao, thai va
luc van » luoc van, luu van, duc van
cac luc » cau luc, coc luc, cac nuoc
ca tren » cau tren, cu tren, la tren
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va
ty nang » ky nang, ty xang, ty hang
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 ty nang ((o hoi) or (o hai)). ((hieu ve) or (hieu van)) cac luc van khanh thai ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((o hoi) OR (o hai)). ((hieu ve) OR (hieu van)) cac luc van khanh thai ca tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((o hoi) or (o hai)). ((hieu ve) or (hieu van)) cac luc van khanh thai ca tren*.