Discovery of the thallium, lead, bismuth, and polonium isotopes
  Currently, forty-two thallium, forty-two lead, forty-one bismuth, and forty-two polonium 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