@article{RISC228,
author = {G. Landsmann and J. Schicho and F. Winkler},
title = {{The Parametrization of Canal Surfaces and the Decomposition of Polynomials into a Sum of Two Squares}},
language = {english},
journal = {Journal of Symbolic Computation},
volume = {32},
number = {1&2},
pages = {119--132},
isbn_issn = {ISSN 0747-7171},
year = {2001},
refereed = {yes},
length = {16}
}