Perhaps you should try some spelling variations:
upon conversations » union conversations, open conversations, spoken conversations
bief history » brief hystory, imf history, reef history
20th century » 18th century
ref history » reef history, imf history, etf history
21 germany » 11 germany, 2 germany, 20 germany
2020 20th » 2020 16th, 2020 2021, 2020 5th
agent » agents

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: %christian ((upon conversations) OR (agent conversations)) %21 germany %((ref history) OR (((bief history) OR (brief history)))) %2020 20th century%22.
• Adding a wildcard symbol may retrieve word variants: %christian ((upon conversations) or (agent conversations)) %21 germany %((ref history) or (((bief history) or (brief history)))) %2020 20th century%22*.