Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
viec cac » vien cac, viec cua, viec lam
van hang » van khang, van hoang, van thang
cao khoa » lao khoa, bao khoa, cac khoa
cac thu » cach thuc, cac thoi
va hang » va nang, va lang, va hanh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cao hoa » cao hoat, cau hoa, cao hoc
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang ((cao hoa) or (cao khoa)). hieu viec cac thu ((va hang) OR (van hang)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((cao hoa) OR (cao khoa)). hieu viec cac thu ((va hang) OR (van hang)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((cao hoa) or (cao khoa)). hieu viec cac thu ((va hang) OR (van hang)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((cao hoa) or (cao khoa)). hieu viec cac thu ((va hang) OR (van hang)) di cua tre*.