From 1967, a nicely illustrated description of various Atlas derivatives:
PDF Review: “Advanced Atlas Launch Vehicle Digest”This was one of the "NASA-NTRS security freakout" victims from March 2013. But the PDF has been posted there.
PDF Review: “Advanced Atlas Launch Vehicle Digest”This was one of the "NASA-NTRS security freakout" victims from March 2013. But the PDF has been posted there.