Orthogonal Constant Mappings in Isosceles Orthogonal Spaces
  In this paper we introduce the notion of orthogonally constant mapping in an isosceles orthogonal space and establish stability of orthogonally constant mappings. As an application, we discuss the orthogonal stability of the Pexiderized quadratic equation $f(x+y)+g(x+y)=h(x)+k(y)$. 
M. Mirzavaziri and M. S. Moslehian