Chung, Jae-young, Stability of a generalized quadratic functional equation in Schwartz distributions, Acta mathematica Sinica. English series (Print) , 25(9), 2009, pp. 1459-1468
We consider the Hyers-Ulam stability problem of the generalized quadratic functional equation u.A+v.B.2w.P1.2..P2=0, which is a distributional version of the classical generalized quadratic functional equation f(x+y)+g(x.y).2h(x).2k(y)=0.