Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu viec » nhieu viec, hieu ve, sieu viet
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
hanh di » hanh vi, hanh de, hang di
thu van » thuc van, thuy van, tu van
cac thu » cach thuc, cac thoi
cau tre » cau tren, cau treo, cau tra
sach ky » sac ky, sach y, sach ty
di cau » da cau, diem cau
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 ky nang ((x hoi) or (o hoi)). ((hieu viec) or (hieu hien)) cac thu van hanh di cau tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). ((hieu viec) OR (hieu hien)) cac thu van hanh di cau tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (o hoi)). ((hieu viec) or (hieu hien)) cac thu van hanh di cau tre*.