Does this 18th-century German quotation include a source?

Question

While researching for a separate question,¹ I came across a book published in German in 1778 by the historian D. H. Hering. He records an interesting anecdote about Martin Luther, which was later published in English but without the surrounding context.

The quotation appears in Historische Nachricht, starting on page 126 and going until 128. The typeface is difficult for me to decipher, so Google Translate isn't an option.² My question relates to a section on page 128:

After the last three lines of the quote, it appears to me that Hering provides a source for the story he has just shared. Am I correct? If so, what is the work being referenced (in modern script)? And if not, are there other clues nearby that indicate where Hering got this quotation?

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_{1. The question I am working on is Did Luther say he “might well have entrusted the whole affair of this [Eucharist] controversy to [Calvin] from the beginning”?. If you prefer to answer that question rather than this one, that's fine with me! 2. I hope this question qualifies as requiring a "profound knowledge of German": my own knowledge is far below basic, so I am not a good judge of that.}

Answer 1

It indeed seems to be a reference. The text reads Ausführliche Behauptung der verbesserten augsp. Confession (1621 4.) S. 311. f. (S. is Seite, page); the modern spelling with the abbreviation expanded would be Ausführliche Behauptung der verbesserten augsburgischen Konfession. That text is mentioned as an anonymous treatise on page 80 of Soll das Augsburger Bekenntnis Grundbekenntnis der Evangelischen Kirche in Deutschland werden?.