Giovanni Battista Costanzi
Giovanni Battista Costanzi (1704-1778) was an Italian composer and cellist. He succeeded Stefano Fabri as maestro di cappella of the Cappella Giulia at St. Peter's Basilica in Rome. Also known as teacher of Luigi Boccherini, to him is dedicated the opera house main theatre in Rome. 
- Giovanni Battista Costanzi', in New Grove Dictionary of Music and Musicians, vol. vi, pp. 527–8.
- 'Giovanni Battista Costanzi', in New Grove Dictionary of Opera, vol. i, p. 971.