BROOKS, Courtney G.; GRIMWOOD, James M.; SWENSON JR., Loyd S. Chariots for Apollo: A History of Manned Lunar Spacecraft [online]. NASA, 1979 [cit. 2012-05-07]. Kapitola The Slow Recovery. Dostupné online. (anglicky)
BROOKS, Courtney G.; GRIMWOOD, James M.; SWENSON JR., Loyd S. Chariots for Apollo: A History of Manned Lunar Spacecraft [online]. NASA, 1979 [cit. 2012-05-07]. Kapitola The Slow Recovery. Dostupné online. (anglicky)