Discovery of dysprosium, holmium, erbium, thulium and ytterbium isotopes
  Currently, 31 dysprosium, 32 holmium, 32 erbium, 33 thulium and 31 ytterbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented. 
C. Fry and M. Thoennessen
nucl-ex