Perhaps you should try some spelling variations:
upon conversations » union conversations, spoken conversations, human conversations
open conversations » agent conversations, roman conversations, content conversations
reef history » brief history, reeves history, reef fishery
ref history » brief history, bief history, imf history
21 germany » 2.1 germany, 11 germany, 2 germany

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 (open conversations)) %21 germany %((ref history) OR (reef history)) %2023 ((20th century) OR (18th century))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%christian ((upon conversations) OR (open conversations)) %21 germany %((ref history) or (reef history)) %2023 ((20th century) or (18th century))%22".
• Adding a wildcard symbol may retrieve word variants: %christian ((upon conversations) OR (open conversations)) %21 germany %((ref history) or (reef history)) %2023 ((20th century) or (18th century))%22*.