National Retail Federation (2007), “National Retail Federation 4-5-4 Calendar,” http://www.nrf.com/.

Technical Committee ISO/TC 154, D. E., Processes, Documents in Commerce, I., and Administration (2004), ISO 8601:2004 Data Elements and Interchange Formats—Information Interchange—Representation of Dates and Times, 3rd Ed., Technical report, International Organization for Standardization.