Perhaps you should try some spelling variations:
20th century » 18th century
21 germany » 2.1 germany, 11 germany, 1 germany
20 germany » 7 germany, 8 germany, 6 germany
2 germany » 7 germany, 2 german, 8 germany
5 germany » 7 germany, 5 german, 8 germany
2f 20th » 20 20th, 2.2 20th

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 %((2 germany) OR (((21 germany) OR (((20 germany) OR (5 germany)))))) %brief history %2f 20th century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%22agriculture and state %((2 germany) or (((21 germany) or (((20 germany) OR (5 germany)))))) %brief history %2f 20th century%22".
• Adding a wildcard symbol may retrieve word variants: %22agriculture and state %((2 germany) or (((21 germany) or (((20 germany) OR (5 germany)))))) %brief history %2f 20th century%22*.