Perhaps you should try some spelling variations:
"amateur astronomical" » "amateur astronomers", "amateur astronomer's", "other astronomical"
"amateur astronomie" » "amateur astronomers", "amateur astronomer's", "mehr astronomie"
"amateur astronomy" » "amateur astronomers"
"amateur astronomer" » "amateur astronomers"

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: (("amateur astronomer") OR ((((("amateur astronomie") OR ("amateur astronomical"))) OR ("amateur astronomy")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"amateur astronomer\") or (((((\"amateur astronomie\") OR (\"amateur astronomical\"))) or (\"amateur astronomy\"))))".
• Removing quotes may allow a broader search: (( amateur astronomer ) or ((((( amateur astronomie ) OR ( amateur astronomical ))) or ( amateur astronomy )))).
• Adding a wildcard symbol may retrieve word variants: (("amateur astronomer") or ((((("amateur astronomie") OR ("amateur astronomical"))) or ("amateur astronomy"))))*.