Discovery of Rubidium, Strontium, Molybdenum, and Rhodium Isotopes
  Currently, thirty-one rubidium, thirty-five strontium, thirty-five molybdenum and thirty-eight rhodium 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. 
A. M. Parker and M. Thoennessen
nucl-ex