Perhaps you should try some spelling variations:
closed environment » cloud environment, crowded environment, cloud environments
field environment » food environment, world environment, lipid environment
oecd environment » oecd environmental, covid environment, grid environment
policy papers » policy paper, policy part

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 environment) OR (field environment))) OR (closed environment)) policy papers.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((oecd environment) OR (field environment))) or (closed environment)) policy papers".
• Adding a wildcard symbol may retrieve word variants: ((((oecd environment) OR (field environment))) or (closed environment)) policy papers*.