GPS Sources with High Peak Frequencies

We have found two extreme GPS sources with peak frequencies of 20 and 30 GHz. The sources are both associated with X-ray bright, low redshift ( z < 1) quasars. We have undertaken a search for similar sources using the Green Bank 5 GHz, NVSS 1.4 GHz surveys and follow-up observations with the Ryle Telescope at 15 GHz and the VLA up to 43 GHz.