Steps toward the power spectrum of matter. III. The primordial spectrum
  Observed power spectrum of matter found in Papers I and II is compared with analytical power spectra. Spatially flat cold and mixed dark matter models with cosmological constant and open models are considered. The primordial power spectrum of matter is determined using the power spectrum of matter and the transfer functions of analytical models. The primordial power spectrum has a break in amplitude. We conclude that a scale-free primordial power spectrum is excluded if presently available data on the distribution of clusters and galaxies represent the true mass distribution of the Universe. 
J. Einasto, M. Einasto, E. Tago, A.A. Starobinsky, F. Atrio-Barandela,   V. M"uller, A. Knebe, and R. Cen