Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
viec cac » vien cac, viec cua, viec lam
van hanh » van thanh, ban hanh, van ban
tai cua » thai cua, tai cuc, tri cua
van anh » van thanh, tuan anh, van minh
tu sach » thu sach, su sach, te sach
cac xuc » cam xuc, cac nuoc, chat xuc
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
o hoi » o hoc, o hai, 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 ky nang ((o hoi) or (co hoi)). hieu viec cac xuc ((van hanh) OR (van anh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (co hoi)). hieu viec cac xuc ((van hanh) OR (van anh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (co hoi)). hieu viec cac xuc ((van hanh) OR (van anh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (co hoi)). hieu viec cac xuc ((van hanh) OR (van anh)) tai cua tre*.