Tecmark, “Smartphone Usage Statistics 2014: UK Survey of Smartphone Users”, October 8, 2014, http://www.tecmark.co.uk/smartphone-usage-data-uk-2014.
26
Miller, George A., “The Challenge of Universal Literacy”, Science 241 (September 9, 1988), p. 1293.
27
Madison, James H., “Changing Patterns of Urban Retailing: The 1920s”, Business and Economic History, vol. 5 (1976), p. 104, http://www.thebhc.org/sites/default/files/beh/BEHprint/v005/p0102-p0111.pdf.
