Perhaps you should try some spelling variations:
khanh thai » nhanh thai, khanh thanh, khanh thuan
van khanh » van thanh, van hanh, van anh
thu sach » tu sach, thuat sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cac xuc » cam xuc, chat xuc, cac cuoc
thai cu » thai cua, thai xu, thi cu
cu tren » tu tren, dua tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
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: thu sach ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van khanh thai cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((o hoi) OR (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van khanh thai cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van khanh thai cu tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ((o hoi) or (o hai)). hieu ve ((cac xuc) OR (cac nuoc)) van khanh thai cu tren*.