12
D. J. Hand, F. Daly, A. D. Lunn, K. J. McConway, and E. Ostrowski, A Handbook of Small Data Sets (London: Chapman and Hall, 1994).
13
D. J. Hand, “Statistical challenges of administrative and transaction data (with discussion),” Journal of the Royal Statistical Society, Series A181 (2018): 555-605.
14
https://www.quora.com/How-many-credit-and-debit-card-transactions-are-there-every-year, accessed 24 August 2018.