Although he reached inconsistent results, an improved formula studied by Hartle, J. Garcia, and based on the works by E. Elizalde includes the technique of the zeta regularization algorithm
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Cardy, John ; Scaling and Renormalization in Statistical Physics, Cambridge University Press (1996) ISBN 0-521-49959-3.
Beside his work on the LSZ formalism he is also known for the development of Bogolyubov - Parasiuk renormalization schema (also BPHZ Renormalization schema named after Klaus Hepp and Zimmermann).