Perhaps you should try some spelling variations:
"closed environment working papers" » "cloud environment working papers", "crowded environment working papers", "cloud environments working papers", "closed environment working paper"
"covid environment working papers" » "cold environment working papers", "cloud environment working papers", "grid environment working papers", "covid environment working paper"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"covid environment working papers\") OR (\"closed environment working papers\"))*".
• Removing quotes may allow a broader search: (( covid environment working papers ) OR ( closed environment working papers ))*.