Perhaps you should try some spelling variations:
military acts » military art, military actions, military aspects
2f history » imf history, etf history, ref history
2019 20th » 2019 4th, 2019 6th, 2019 5th
2.1 20th » 2.2 20th, 2021 20th, 2017 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) OR (2019 20th)) century%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%military acts and science %2f history %((2.1 20th) OR (2019 20th)) century%22".
• Adding a wildcard symbol may retrieve word variants: %military acts and science %2f history %((2.1 20th) OR (2019 20th)) century%22*.