I suspect somewhat of peculiar in his way of ciphering six letters from the French court to the Count of Lauzun in Ireland from 1690 - Biermann, Norbert 1968- (Universität der Künste Berlin, Universitätsbibliothek, 2021)
"This is a working paper and has not been peer-reviewed. The author gladly accepts notices of inaccuracies or errors"