Saya mau tau Pranala dari Vix Pervenit

Carlen, C. (ed.). 1990. The Papal Encyclicals, Vol. I. Raleigh, N.C. p. 15-17.

Moehlman, Conrad H. 1934. "The Christianization of Interest." Church History. Issue 3. p. 3-15.

Pollard, John F. 2005. Money and the Rise of the Modern Papacy: Financing the Vatican, 1850–1950. Cambridge University Press. p. 26.