@article{RSMUP_2011__125__39_0,
     author = {Martini, H. and Mozgawa, W.},
     title = {An integral formula related to inner isoptics},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {39--50},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {125},
     year = {2011},
     mrnumber = {2865958},
     zbl = {1252.52003},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_2011__125__39_0/}
}