Perhaps you should try some spelling variations:
serious conversation » curious conversations, serious conideration, versus conversation
union conversations » win conversations, design conversations, driven conversations
20th century » 18th century
ref history » reef history, brief history, bief history
21 germany » 11 germany, 20 germany, 7 germany
2 germany » 7 germany, 2 german, 8 germany
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 ((union conversations) OR (serious conversation)) %((2 germany) OR (21 germany)) %ref history %2f 20th century%22.
• Adding a wildcard symbol may retrieve word variants: %22christian ((union conversations) or (serious conversation)) %((2 germany) or (21 germany)) %ref history %2f 20th century%22*.