Perhaps you should try some spelling variations:
christian upon » christians upon, christianity upon, christ upon
ref history » reef history, brief history, bief history
21 germany » 2.1 germany, 11 germany, 2 germany
2021 20th » 2020 20th, 2021 10th, 2023 20th
2021 24th » 2021 4th, 2021 6th, 2021 7th

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 %ref history %((2021 20th) OR (2021 24th)) century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((christian upon) or (christian union)) conversations %21 germany %ref history %((2021 20th) OR (2021 24th)) century%22".
• Adding a wildcard symbol may retrieve word variants: %((christian upon) or (christian union)) conversations %21 germany %ref history %((2021 20th) OR (2021 24th)) century%22*.