One of the major problems using quasars to investigate the Hubble diagram is an uncertainty as to the size of the bolometric correction. Some estimates have suggested that it may be as high as 6 magnitudes. To this end, the authors have compiled data from a wide range of sources, to investigate the behaviour of quasar spectra over the range from radio to X-rays, and hence to be able to calculate this important parameter. Here they present a sample of the compiled spectra, whilst a complete catalogue of around two hundred spectra is in preparation.