Perhaps you should try some spelling variations:
covid environment » cold environment, closed environment, cloud environment
field environment » food environment, world environment, wind environment
working papers » working paper

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: ((((oecd environmental) OR (covid environment))) OR (field environment)) working papers.
• Adding a wildcard symbol may retrieve word variants: ((((oecd environmental) or (covid environment))) or (field environment)) working papers*.