  It is proved in this paper that continuum set of $L_2$-orthogonal systems
generated by the Riemann zeta-function on the critical line corresponds to
every fixed $L_2$-orthogonal system on a fixed segment. This theorem serves as
a resource for new set of integrals not accessible by the current methods in
the theory of the Riemann zeta-function.
  \noindent Dedicated to the 100th anniversary of G.H. Hardy's fundamental
theorem: the function $\zf$ has an infinite set of zeros, \cite{1}.
