Discovery of the astatine, radon, francium, and radium isotopes
  Currently, thirty-nine astatine, thirty-nine radon, thirty-five francium, and thirty-four radium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented. 
C. Fry and M. Thoennessen
nucl-ex