Sewell, Stephen 'Cookie' (1998). “Why Three Tanks?”Archived 2016-03-04 at the Wayback Machine (PDF) in Armor vol. 108, no. 4, p. 21. Fort Knox, KY: US Army Armor Center. ISSN 0004-2420.
Sewell, Stephen 'Cookie' (1998). “Why Three Tanks?”Archived 2016-03-04 at the Wayback Machine (PDF) in Armor vol. 108, no. 4, p. 21. Fort Knox, KY: US Army Armor Center. ISSN 0004-2420.