Perhaps you should try some spelling variations:
ref history » reef history, brief history, bief history
21 germany » 11 germany, 2 germany, 20 germany
2023 20th » 2023 26th, 2023 10th, 2020 20th
1990 20th » 1995 20th, 1999 20th, 1994 20th
94 20th » 4 20th, 90 20th, 1994 20th
94 24th » 94 4th, 94 14th, 24 24th

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: %22agriculture AND state %21 germany %ref history %((2023 20th) OR (((1990 20th) OR (((94 20th) OR (94 24th)))))) century%22.
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %21 germany %ref history %((2023 20th) or (((1990 20th) or (((94 20th) or (94 24th)))))) century%22*.