Perhaps you should try some spelling variations:
nhieu viec » nhien viet
hieu viec » hieu ve, sieu viet, hieu hien
cao hoat » cac hoat, co hoat, cao chat
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
va hang » van hang, va nang, va lang
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
cac tu » cac thu, cach tu, cac du
va cua » va chua, via cua, ca cua

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) OR (su sach)) y nang cao hoat. ((hieu viec) OR (nhieu viec)) cac tu va hang va cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) y nang cao hoat. ((hieu viec) OR (nhieu viec)) cac tu va hang va cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang cao hoat. ((hieu viec) OR (nhieu viec)) cac tu va hang va cua tre*.