[1] The above Wikipedia article uses σ to denote the capital output ratio. The symbol ν is used more ofter for the capital output ratio while σ more often denotes the output capital ratio 1/ν. To avoid confusion, in this study σ denotes the capital output ratio, consistent with the Wikipedia article linked.
[2] The Macrodynamics of Capitalism, p 33,
2d ed, Springer-Verlag, 2009