Perhaps you should try some spelling variations:
van khanh » van thanh, van hanh, van anh
cac vung » cac ung, cac chung, cach dung
vung van » vung va, dung van, vung ven
thai cuu » thai cua, thi cuc, thai xu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
co dai » co dan, do dai
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (co dai)). hieu ve cac vung van khanh ((thai cuu) OR (tai cuc)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (co dai)). hieu ve cac vung van khanh ((thai cuu) OR (tai cuc)) tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (co dai)). hieu ve cac vung van khanh ((thai cuu) OR (tai cuc)) tre*.