Radiochemical methods for preparing sources of internal conversion electrons for the γ-transitions of ^57m Fe (14.4 keV), ¹²⁹Te (27.77 keV), ¹²⁷Te (57.60. keV), and ^127m Te (88.26 keV) were suggested. The sources are intended for studying the conversion of nuclear transitions on external shells of cobalt and tellurium compounds. The chemical state of these elements is monitored by Mössbauer spectroscopy.