Jim Schaefer; M.L. Elrick; Todd Spangler (October 7, 2007). "Ready for battle". The Detroit Free Press. Archived from the original on November 26, 2015. Retrieved October 7, 2007.
U.S. House of Representatives, Permanent Select Committee on Intelligence (November 30, 2017). "Testimony of Erik Prince"(PDF). U.S. House of Representatives. Retrieved July 23, 2019.
Boyd, Stephen Elliott (February 4, 2020). "Dear Chairman Schiff". Letter to Adam Schiff. Archived from the original on February 5, 2020. Retrieved February 5, 2020.
Jim Schaefer; M.L. Elrick; Todd Spangler (October 7, 2007). "Ready for battle". The Detroit Free Press. Archived from the original on November 26, 2015. Retrieved October 7, 2007.
Boyd, Stephen Elliott (February 4, 2020). "Dear Chairman Schiff". Letter to Adam Schiff. Archived from the original on February 5, 2020. Retrieved February 5, 2020.