Perhaps you should try some spelling variations:
curious conversations » curious conversion, courageous conversations, conscious conversations
serious conversation » serious conideration, versus conversation, ingenious conversation
20th century » 18th century
ref history » reef history, bief history, etf history
12 german » 2 german, 2012 german
2f 20th » 20 20th, 2.2 20th

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: %22christian ((curious conversations) OR (serious conversation)) %12 german %((ref history) OR (((imf history) OR (brief history)))) %2f 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22christian ((curious conversations) or (serious conversation)) %12 german %((ref history) or (((imf history) OR (brief history)))) %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22christian ((curious conversations) or (serious conversation)) %12 german %((ref history) or (((imf history) OR (brief history)))) %2f 20th century%22*.