Welcome to GM Authentic Autographs! Information About this Item. Autograph By: All 5 members of RADIOHEAD. Includes a signed Certificate of Authenticity from GM Authentic Autographs. They obtain each individual autograph in person and provide a detailed description of where the item was signed on a GMAA Certificate of Authenticity. While most of the autographs in our inventory are obtained in New York City, GMAA also travels to select film…