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"1999 OUN Tornado Warning #37". National Weather Service Norman, Oklahoma. May 3, 1999. Archived from the original on April 19, 2011. Retrieved October 20, 2015 – via Iowa Environmental Mesonet.
James Murnan (April 20, 2009). "Remembering May 3, 1999". National Weather Service Forecast Office, Norman, Oklahoma. National Oceanic and Atmospheric Administration. Archived from the original on October 12, 2010. Retrieved October 1, 2010.
ncdc.noaa.gov
"Storm Events Database – Event Details". National Climatic Data Center. National Oceanic and Atmospheric Administration. May 3, 1999. Archived from the original on January 31, 2020. Retrieved March 14, 2014.
Daniel J. Miller; Charles A. Doswell III; Harold E. Brooks; Gregory J. Stumpf; Erik Rasmussen (1999). "Highway Overpasses as Tornado Shelters". National Weather Service in Norman, Oklahoma. p. 1. Archived from the original on November 13, 2010. Retrieved October 3, 2010.
James Murnan (April 20, 2009). "Remembering May 3, 1999". National Weather Service Forecast Office, Norman, Oklahoma. National Oceanic and Atmospheric Administration. Archived from the original on October 12, 2010. Retrieved October 1, 2010.
"1999 OUN Tornado Warning #37". National Weather Service Norman, Oklahoma. May 3, 1999. Archived from the original on April 19, 2011. Retrieved October 20, 2015 – via Iowa Environmental Mesonet.
"Doppler on Wheels". Center for Severe Weather Research. 2010. Archived from the original on February 5, 2007. Retrieved October 1, 2010.
"Storm Events Database – Event Details". National Climatic Data Center. National Oceanic and Atmospheric Administration. May 3, 1999. Archived from the original on January 31, 2020. Retrieved March 14, 2014.
Jim LaDue; Tim Marshall; Kevin Scharfenberg (2012). "Discriminating EF4 and EF5 Tornado Damage"(PDF). National Weather Service Forecast Office, Norman, Oklahoma. National Oceanic and Atmospheric Administration. Archived from the original on January 9, 2016. Retrieved June 26, 2013.
"Plains States Tornado Update" (Press release). Federal Emergency Management Agency. May 6, 1999. Archived from the original on June 7, 2010. Retrieved October 2, 2010.
Daniel J. Miller; Charles A. Doswell III; Harold E. Brooks; Gregory J. Stumpf; Erik Rasmussen (1999). "Highway Overpasses as Tornado Shelters". National Weather Service in Norman, Oklahoma. p. 1. Archived from the original on November 13, 2010. Retrieved October 3, 2010.
Jim LaDue; Tim Marshall; Kevin Scharfenberg (2012). "Discriminating EF4 and EF5 Tornado Damage"(PDF). National Weather Service Forecast Office, Norman, Oklahoma. National Oceanic and Atmospheric Administration. Archived from the original on January 9, 2016. Retrieved June 26, 2013.