  Albeit essential corrections are required both in his claim and in his
argument, N.V. Kuznetsov observed in his Bombay article (*) of 1989 a highly
interesting transformation formula for spectral sums of products of four values
of modular Hecke L-functions. A complete proof of a corrected version of the
formula was later supplied by the present author in 1991, which has, however,
remained unpublished for more than a decade, except for a limited distribution.
The aim of the present paper is to reproduce this proof of the author with some
sophistications, retaining the original style as much as possible. (*) He
claimed a resolution of the eighth moment problem of the Riemann zeta-function.
But his argument is fatally incorrect. Our paper here concerns an essential
ingredient in his argument, but we claim nothing about the eighth moment
itself.
