Perhaps you should try some spelling variations:
khanh tai » thanh tai, hanh tai, nhanh thai
van khanh » van thanh, van hanh, van anh
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
cuc tre » duc tre, cua tre, cuu tre
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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