Perhaps you should try some spelling variations:
26 economics » 2.6 economics, 16 economics, 26 economic
26 personnel » 2 personnel, 22 personnel, 24 personnel
20 personnel » 2 personnel, _ personnel, du personnel
29 personnel » 2 personnel, _ personnel, du personnel
6 economics » 6 economic, 1 economics, 5 economics
a personnel » _ personnel, du personnel, care personnel
2f human » 22 human, 23 human, 27 human
20 human » 10 human
21 human » 1 human, 11 human

Try widening your search to All Fields.

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: %22business %((26 economics) OR (6 economics)) %((((2f human) OR (20 human))) OR (21 human)) resources %((((26 personnel) OR (((20 personnel) OR (29 personnel))))) OR (a personnel)) management%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22business %((26 economics) or (6 economics)) %((((2f human) OR (20 human))) or (21 human)) resources %((((26 personnel) or (((20 personnel) or (29 personnel))))) or (a personnel)) management%22".
• Adding a wildcard symbol may retrieve word variants: %22business %((26 economics) or (6 economics)) %((((2f human) OR (20 human))) or (21 human)) resources %((((26 personnel) or (((20 personnel) or (29 personnel))))) or (a personnel)) management%22*.