Perhaps you should try some spelling variations:
"world bank working paper" » "world black working paper", "world manko working paper", "world pack working paper", "world bank working papers"
"world band working paper" » "world bandes working paper", "world board working paper", "world based working paper", "world brand working paper", "world hand working paper", "world bandar working paper", "world band working papers"
"world bond working paper" » "world bonds working paper", "world bold working paper", "world bone working paper", "world beyond working paper", "world board working paper", "world blind working paper", "world bond working papers"

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: (((("world band working paper") OR ("world bank working paper"))) OR ("world bond working paper")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"world band working paper\") OR (\"world bank working paper\"))) or (\"world bond working paper\"))".
• Removing quotes may allow a broader search: (((( world band working paper ) OR ( world bank working paper ))) or ( world bond working paper )).
• Adding a wildcard symbol may retrieve word variants: (((("world band working paper") OR ("world bank working paper"))) or ("world bond working paper"))*.