Perhaps you should try some spelling variations:
20th century » 18th century
2.1 germany » 2017 germany, 9.13 germany, 9.14 germany
ref history » reef history, brief history, bief history
21 germany » 11 germany, 8 germany, 5 germany
20 germany » 8 germany, 5 germany, 6 germany
2 germany » 2 german, 8 germany, 5 germany
20 20th » 90 20th, 2019 20th, 2020 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: %22agriculture AND state %((((((21 germany) OR (20 germany))) OR (2.1 germany))) OR (((2 germany) OR (7 germany)))) %ref history %20 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((((((21 germany) OR (20 germany))) or (2.1 germany))) or (((2 germany) or (7 germany)))) %ref history %20 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((((((21 germany) OR (20 germany))) or (2.1 germany))) or (((2 germany) or (7 germany)))) %ref history %20 20th century%22*.