Perhaps you should try some spelling variations:
"staff working papers; working paper" » "start working papers; working paper", "state working papers; working paper", "stack working papers; working paper"
"hf working papers; working paper" » "adf working papers; working paper", "imf working papers; working paper", "off working papers; working paper"

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: (("hf working papers; working paper") OR ("staff working papers; working paper")).
• Removing quotes may allow a broader search: (( hf working papers; working paper ) or ( staff working papers; working paper )).
• Adding a wildcard symbol may retrieve word variants: (("hf working papers; working paper") or ("staff working papers; working paper"))*.