Kershner, C. J.; DeSando, R. J. & Heidelberg, R. F. et al. (1966), "Rare earth polonides", J. Inorg. Nucl. Chem.28 (8): 1581–88, DOI 10.1016/0022-1902(66)80054-4. Kershner, C. J. & Desando, R. J. (1970), "Promethium polonide synthesis and characterization", J. Inorg. Nucl. Chem.32 (9): 2911–18, DOI 10.1016/0022-1902(70)80355-4.