Perhaps you should try some spelling variations:
van khanh » van thanh, van anh, van phan
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
cac xuc » cam xuc, cac nuoc, chat xuc
thai cu » thai cua, thai xu, thi cu
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cu tren » tu tren, dua tren
ve cac » va cac, vien cac
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 cac xuc ((van khanh) OR (van hanh)) thai cu 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 cac xuc ((van khanh) OR (van hanh)) thai cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((o hoi) or (o hai)). hieu ve cac xuc ((van khanh) OR (van hanh)) thai cu tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((o hoi) or (o hai)). hieu ve cac xuc ((van khanh) OR (van hanh)) thai cu tren*.