Lewin, C G (1970). "An Early Book on Compound Interest - Richard Witt's Arithmeticall Questions". Journal of the Institute of Actuaries. 96 (1): 121–132. doi:10.1017/S002026810001636X.
Lewin, C G (1981). "Compound Interest in the Seventeenth Century". Journal of the Institute of Actuaries. 108 (3): 423–442. doi:10.1017/S0020268100040865.
Milanfar, Peyman (1996). "A Persian Folk Method of Figuring Interest". Mathematics Magazine. 69 (5): 376. doi:10.1080/0025570X.1996.11996479.