Gregorian Reform of the Calendar: Proceedings of the Vatican Conference to Commemorate its 400th Anniversary (1582-1982)

This is the only book I've been able to find on the history of the Gregorian Calendar reform. UPDATE: I found this: [a transcription of Clavius's algorithm (Latin+French translation)](https://isidore.co/calibre/#panel=book_details&book_id=7778)! Original source: [ADS](http://articles.adsabs.harvard.edu//full/book/grc../1983//0000001) See also [this answer regarding " *stylus"*](https://christianity.stackexchange.com/a/62535/1787) *.*