Bibliography
- Amson , John, C . 2008 . Gregory's meridian line of 1673–74: a St Andrews detective story . BSHM Bulletin , 23 : 58 – 72 .
- ‘Astronomia in Cattedrale’, Opera di Santa Maria del Fiore at http://www.operaduomo.firenze.it/english
- Heilbron , John L . 1999 . The sun in the church: cathedrals as solar observatories , Harvard University Press . at http://cis.alma.unibo.it/NewsLetter/090496Nw/Heilbron.htm