@techreport{G-ap-sstvc-01b
,   category   = "report"
,   author     = {P.~Angelier and M.~Pocchiola}
,   title      = {A sum of squares theorem for visibility complexes and applications}
,   number     = {G-LIENS-01-1}
,   institution= {Department of Computer Science, Ecole normale supérieure Paris}
,   address    = {France}
,   year       = 2001
,   month      = {August}
}                                                                               

@inproceedings{G-ap-sstvc-01
, category    = "intc"
,   author    = {P. Angelier and M.~Pocchiola}
,   title     = {A sum of squares theorem for visibility complexes}
,   booktitle = {Proc. 17th Annu. ACM Sympos. Comput. Geom.}
,   year      = 2001
,   pages     = "302--311"
,   note      = {}
}