1. : Integral operators in the theory of linear partial differential equations. Ergeb. Math. u. Grenzgeb. 23, Springer Verlag, Heidelberg 1969.
2. et al.: MACSYMA-Reference manual, version ten. Symbolics Inc., Cambridge, MA 1984.
3. ; : On the numerical treatment of partial differential equations by function theoretic methods. In: Proc. Sympos. Numerical Solution of Partial Differential Equations, University of Maryland, May 1970, Academic Press, New York 1971.