Bergeron, D E; Collins, S M; Pibida, L; Cessna, J T; Fitzgerald, R; Zimmerman, B E; Ivanov, P; Keightley, J D; Napoli, E (2021) Ra-224 activity, half-life, and 241 keV gamma ray absolute emission intensity: A NIST-NPL bilateral comparison. Applied Radiation and Isotopes, 170. 109572 ISSN 09698043