Brownlee, John (1915). "Historical note on Farr's theory of the epidemic". The British Medical Journal, Part 2. 2 (2850): 250–252. doi:10.1136/bmj.2.2850.250. PMC2302838. PMID20767766. From p. 250: "He specially considered the decline of the [smallpox] epidemic, and fitted the figures to a curve calculated by a method described. Though he gives no equation of the form of the curve, it is quite obviously the normal curve of error."
Farr, William (1840). "Causes of death in England and Wales". Second Annual Report of the Registrar General of Births, Deaths and Marriages in England. 2: 69–98. On p. 97, Farr stated that during a recent smallpox epidemic, the number of deaths versus time followed a roughly normal curve: "The rates vary with the density of the population, the numbers susceptible of attack, the mortality, and the accidental circumstances; so that to obtain the mean rates applicable to the whole population, or to any portion of the population, several epidemics should be investigated. It appears probable, however, that the small-pox increases at an accelerated and then a retarded rate; that it declines first at a slightly accelerated, and at a rapidly accelerated, and lastly at a retarded rate, until the disease attains the minimum intensity, and remains stationary."
Brownlee, John (1915). "Historical note on Farr's theory of the epidemic". The British Medical Journal, Part 2. 2 (2850): 250–252. doi:10.1136/bmj.2.2850.250. PMC2302838. PMID20767766. From p. 250: "He specially considered the decline of the [smallpox] epidemic, and fitted the figures to a curve calculated by a method described. Though he gives no equation of the form of the curve, it is quite obviously the normal curve of error."
Brownlee, John (1915). "Historical note on Farr's theory of the epidemic". The British Medical Journal, Part 2. 2 (2850): 250–252. doi:10.1136/bmj.2.2850.250. PMC2302838. PMID20767766. From p. 250: "He specially considered the decline of the [smallpox] epidemic, and fitted the figures to a curve calculated by a method described. Though he gives no equation of the form of the curve, it is quite obviously the normal curve of error."
Brownlee, John (1915). "Historical note on Farr's theory of the epidemic". The British Medical Journal, Part 2. 2 (2850): 250–252. doi:10.1136/bmj.2.2850.250. PMC2302838. PMID20767766. From p. 250: "He specially considered the decline of the [smallpox] epidemic, and fitted the figures to a curve calculated by a method described. Though he gives no equation of the form of the curve, it is quite obviously the normal curve of error."
