Günter Landsmann, Franz Winkler, Josef Schicho,
"The Parametrization of Canal Surfaces and the Decomposition of Polynomials into a Sum of Two Squares"
, in Journal of Symbolic Computation, Vol. 32, Nummer 1&2, 3-2001, ISSN: 1095-855X, J. Of Symbolic Computation, 32/1/2, 119-132, 2001
Original Titel:
The Parametrization of Canal Surfaces and the Decomposition of Polynomials into a Sum of Two Squares