Fries, Colin (March 13, 2015). "Chronology of Wakeup Calls"(PDF). NASA History Division. Archived from the original(PDF) on December 20, 2023. Retrieved November 25, 2022.
Fries, Colin (March 13, 2015). "Chronology of Wakeup Calls"(PDF). NASA History Division. Archived from the original(PDF) on December 20, 2023. Retrieved November 25, 2022.