Perhaps you should try some spelling variations:
christian upon » christians upon, christianity upon, christ upon
20th century » 18th century
ref history » reef history, bief history, imf history
2 germany » 7 germany, 2 german, 8 germany
2020 20th » 2020 16th, 2020 2021, 2020 5th

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) OR (christian union)) conversations %2 germany %((ref history) OR (brief history)) %2020 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((christian upon) or (christian union)) conversations %2 germany %((ref history) OR (brief history)) %2020 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %((christian upon) or (christian union)) conversations %2 germany %((ref history) OR (brief history)) %2020 20th century%22*.