Richards, P.; Tucker, W.D.; Srivastava, S.C. (October 1982). «Technetium-99m: an historical perspective». The International journal of applied radiation and isotopes33 (10): 793-9. PMID6759417. doi:10.1016/0020-708X(82)90120-X.
Stang, Louis G.; Richards, Powell (1964). «Tailoring the isotope to the need». Nucleonics22 (1). ISSN0096-6207.
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Richards, P.; Tucker, W.D.; Srivastava, S.C. (October 1982). «Technetium-99m: an historical perspective». The International journal of applied radiation and isotopes33 (10): 793-9. PMID6759417. doi:10.1016/0020-708X(82)90120-X.
Richards, Powell (1989). Technetium-99m: The Early Days. BNL-43197 CONF-8909193-1. New York: Brookhaven National Laboratory. Consultado el 3 de mayo de 2012.