Publications with shared reference: Distinct HLA‐DR epitopes and distinct families of HLA‐DR molecules defined by 15 monoclonal antibodies (mAb) either anti‐DR or allo‐anti‐Ia<sup>k</sup> crossreacting with human DR molecule. I. Cross‐inhibition studies of mAb cell surface fixation and differential binding of mAb to detergent‐solubilized HLA molecules immobilized to a solid phase by a first mAb