On Determining the Spectrum of Primordial Inhomogeneity from the COBE   DMR Sky Maps: II. Results of Two Year Data Analysis
  A new technique of Fourier analysis on a cut sky (Gorski, 1994) has been applied to the two year COBE DMR sky maps. The Bayesian power spectrum estimation results are consistent with the Harrison-Zel'dovich n=1 model. The maximum likelihood estimates of the parameters of the power spectrum of primordial perturbations are n=1.22 (1.02) and Q_{rms-PS}=17 (20) uK including (excluding) the quadrupole anisotropy. The marginal likelihood function on n renders n=1.10 \pm 0.32 (0.87 \pm 0.36). 
K.M. Gorski, G. Hinshaw, A.J. Banday, C.L. Bennett, E.L. Wright, A.   Kogut, G.F. Smoot & P. Lubin