The Complete Bispectrum of COBE-DMR Four Year Maps
  We extend a previous bispectrum analysis of the COBE-DMR 4 year maps, allowing for the presence of correlations between all possible angular scales. We find that the non-Gaussian signal found earlier for bispectrum components including adjacent modes does not extend to triplets of modes with larger separations. Indeed for all separations $\Delta\ell >1$ we find that the COBE-DMR data is very Gaussian. The implication seems to be that the previously detected non-Gaussian scale-scale correlation falls off very quickly with mode separation. 
H.B. Sandvik and J.Magueijo