National Retail Federation (2007). “National Retail Federation 4-5-4 Calendar.” http://www.nrf.com/.
Technical Committee ISO/TC 154 (Processes, Data Elements, and Documents in Commerce, Industry, 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.