↑ Groos, Arthur (1986). Cambridge Opera Handbooks: La bohème. Cambridge University Press. p. 1. ISBN0521264898. Unknown parameter |coauthors= ignored (|author= suggested) (help)
↑ Budden, Julian (2002). Puccini: His Life and Works. Oxford University Press. p. 494. ISBN9780198164685.
↑ "The Top 20". Opera America. สืบค้นเมื่อ 15 June 2009.