1. On multivariable Sheffer sequences;Brown;J. Math. Anal. Appli.,1969
2. An Introduction to Orthogonal Polynomials;Chihara,1978
3. An Introduction to Orthogonal Polynomials;Chihara,1978
4. An Introduction to Orthogonal Polynomials;Chihara,1978
5. Operator calculus;Feinsilver;Pacific. J. Math.,1978