Perhaps you should try some spelling variations:
"world based working paper" » "world base working paper", "world based parking paper", "world basic working paper", "word based working paper", "world case working paper", "gold based working paper", "world based working papers"
"world band working paper" » "world bandes working paper", "world board working paper", "world hard working paper", "world brand working paper", "world bond working paper", "world hand working paper", "world band working papers"
"world bank working paper" » "world black working paper", "world manko working paper", "world pack working paper", "world bank working papers"
"world bone working paper" » "world one working paper", "world bonn working paper", "world none working paper", "world gone working paper", "world bone 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 based working paper"))) OR ("world bank working paper"))) OR ("world bone working paper")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"world band working paper\") OR (\"world based working paper\"))) or (\"world bank working paper\"))) or (\"world bone working paper\"))".
• Removing quotes may allow a broader search: (((((( world band working paper ) OR ( world based working paper ))) or ( world bank working paper ))) or ( world bone working paper )).
• Adding a wildcard symbol may retrieve word variants: (((((("world band working paper") OR ("world based working paper"))) or ("world bank working paper"))) or ("world bone working paper"))*.