Perhaps you should try some spelling variations:
"astronomy and astrophysics summary" » "astronomy and astrophysics gamma", "astronomy and astrophysics stars", "astronomy and astrophysics sun"
"astronomy and astrophysics saas" » "astronomy and astrophysics stars", "astronomy and astrophysics state", "astronomy and astrophysics sun"

Try widening your search to All Fields.

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("astronomy and astrophysics summary") OR ("astronomy and astrophysics saas")).
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