author = {Erik Hillgarter and G\"unter Landsmann and Josef Schicho and Franz Winkler},
title = {{Generalized Offsets as Envelopes of a One-parameter Set of Spheres}},
number = {99-27},
year = {1999},
month = {September},
keywords = {canal surface, sum of two squares},
sponsor = {Austrian Science Fund (FWF), Proj.Nr. P11160-TEC (HySax), Proj.Nr. P12662-TEC (Adjoints), and the special research area SFB F013, subprojects 03 and 04.},
type = {RISC Report Series},
institution = {Research Institute for Symbolic Computation (RISC), Johannes Kepler University Linz},
address = {Schloss Hagenberg, 4232 Hagenberg, Austria}