Robertson, R. (2001). Karl Beck: From Radicalism to Monarchism. Year Book / Leo Baeck Institute.
Lua i Stíl Chicago (17ú heag.)Robertson, Ritchie. "Karl Beck: From Radicalism to Monarchism." Year Book / Leo Baeck Institute 2001.
Lua MLA (8ú heag.)Robertson, Ritchie. "Karl Beck: From Radicalism to Monarchism." Year Book / Leo Baeck Institute, 2001.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.