Perhaps you should try some spelling variations:
military acts » military art, military actions, military aspects
20th century » 18th century
2f history » imf history, etf history, ref history
2.1 20th » 2.2 20th, 2019 20th, 2021 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: %military acts AND science %2f history %2.1 20th century%22.
• Adding a wildcard symbol may retrieve word variants: %military acts and science %2f history %2.1 20th century%22*.