“…Main results have been discussed by Harker (Harker, 1987), Carmone, Kara and Zanakis (Carmone et al, 1997), Kwiesielewicz and van Uden (Kwiesielewicz, 1996;Kwiesielewicz and van Uden, 2003), Shiraishi, Obata and Daigo (Shiraishi et al, 1998;Shiraishi and Obata, 2002), Takeda and Yu (Takeda and Yu, 1995), Fedrizzi and Giove (Fedrizzi and Giove, 2007).…”