Perhaps you should try some spelling variations:
christian upon » christians upon, christianity upon, christ upon
20th century » 18th century
ref history » reef history, brief history, bief history
21 germany » 2 germany, 20 germany, 1 germany
11 germany » 1918 germany, 7 germany, 8 germany
11 german » 1 german
2021 20th » 2021 24th, 2020 20th, 2021 10th

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 %((21 germany) OR (((11 germany) OR (11 german)))) %ref history %2021 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((christian upon) or (christian union)) conversations %((21 germany) or (((11 germany) OR (11 german)))) %ref history %2021 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %((christian upon) or (christian union)) conversations %((21 germany) or (((11 germany) OR (11 german)))) %ref history %2021 20th century%22*.