Perhaps you should try some spelling variations:
"closed environment working paper" » "cloud environment working paper", "crowded environment working paper", "cloud environments working paper"
"covid environment working papers" » "cold environment working papers", "cloud environment working papers", "grid environment 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: (("covid environment working papers") OR ("closed environment working paper")).
• Removing quotes may allow a broader search: (( covid environment working papers ) or ( closed environment working paper )).
• Adding a wildcard symbol may retrieve word variants: (("covid environment working papers") or ("closed environment working paper"))*.