“…If we replace the symbol A(x, y) by more general symbol a(x, y), which is no longer a polynomial in y necessarily , we get the pseudo-differential operator A c a,θ defined below. For p.d.o., involving Fourier transform, Hankel transform, fractional Fourier transform, Fourier-Jacobi transform and a singular differential operator, we may refer respectively [11,13], [6], [7,9], [10,12] and [2].…”