qPCRplotByRef.png. These show the mean ΔCqvalues for all values following normalisation by a reference gene, in each case ordered by differing reference genes. In this case B2m appears to show the least correlation with the others, suggesting it might be removed when calculating the normalisation factor.
Perkins et al. BMC Genomics 2012 13:296 doi:10.1186/1471-2164-13-296