On the density of stabilizable plants in the class of unstabilizable plants: The real symmetric disk algebra case. - Rudolf Rupp; Amol Sasane (J. Frankl. Inst., 2009)

Mappings into the Euclidean Sphere. - Raymond Mortini; Rudolf Rupp (Am. Math. Mon., 2012)

On two natural extensions of Vinnicombe's metric: their non-coincidence yet equivalence on stabilizable plants over A+. - Rudolf Rupp; Amol Sasane (IMA J. Math. Control. Inf., 2013)