Perhaps you should try some spelling variations:
khanh thanh » nhanh thanh, thanh thanh, hinh thanh
phan thanh » pham thanh, ban thanh, van thanh
tu sach » thu sach, su sach, te sach
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
ve cac » va cac, vien cac
co dai » co dan, do dai
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 vuc van ((khanh thanh) OR (phan thanh)) cuu 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 vuc van ((khanh thanh) OR (phan thanh)) cuu tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (co dai)). hieu ve cac vuc van ((khanh thanh) OR (phan thanh)) cuu tre*.