R. Boughey (June 1977). "Size Labelling of Footwear". Journal of Consumer Studies & Home Economics. 1 (ll2): 123–129. doi:10.1111/j.1470-6431.1977.tb00197.x.
Melissa (30 March 2016). "Why are shoe sizes as they are?". Today I found out. (12×3=36. US(m): 36−22=14, UK: 36−23=13, EU:30.5×1.5=45.75 then +2 "for comfort" plus rounding = 48)