Further comments on "Implications of the Routh stability criterion"

The result of the above-named note (ibid., vol. AC-15 pp 554-555, June 1980) is contained in Routh´s original monograph (1975), where he shows that a polynomial has at least one root with a positive real part if any element in the Routh array is negative. Routh´s work is readily available in the reprinted version, but for some reason this result is seldom quoted in contemporary textbooks.