Martin Peternell, Boris Odehnal, Maria Lucia Sampoli. On quadratic two-parameter families of spheres and their envelopes. Computer Aided Geometric Design, 25(4-5):342-355, 2008. [doi]
@article{PeternellOS08,
title = {On quadratic two-parameter families of spheres and their envelopes},
author = {Martin Peternell and Boris Odehnal and Maria Lucia Sampoli},
year = {2008},
doi = {10.1016/j.cagd.2007.10.007},
url = {http://dx.doi.org/10.1016/j.cagd.2007.10.007},
researchr = {https://researchr.org/publication/PeternellOS08},
cites = {0},
citedby = {0},
journal = {Computer Aided Geometric Design},
volume = {25},
number = {4-5},
pages = {342-355},
}