https://en.wikipedia.org/wiki/Athanasius_Kircher#Combinatorics https://en.wikipedia.org/wiki/Arca_Musarithmica
http://www.treccani.it/enciclopedia/alessandro-vii_(Enciclopedia-dei-Papi) https://en.wikipedia.org/wiki/Pope_Alexander_VII
http://www.treccani.it/enciclopedia/clemente-ix_(Enciclopedia-dei-Papi)/ https://en.wikipedia.org/wiki/Pope_Clement_IX
http://www.treccani.it/enciclopedia/clemente-x_(Enciclopedia-dei-Papi)/ https://en.wikipedia.org/wiki/Pope_Clement_X
http://www.treccani.it/enciclopedia/gian-lorenzo-bernini/ https://en.wikipedia.org/wiki/Gian_Lorenzo_Bernini