Marton, L. (1980). «Ferdinand Braun: Forgotten Forefather». En Suesskind, Charles, ed. Advances in electronics and electron physics50. Academic Press. p. 252. ISBN978-0-12-014650-5. Archivado desde el original el 3 de mayo de 2014. «occurs first in a pair of later papers by Zenneck (1899a,b)».
Marton, L. (1980). «Ferdinand Braun: Forgotten Forefather». En Suesskind, Charles, ed. Advances in electronics and electron physics50. Academic Press. p. 252. ISBN978-0-12-014650-5. Archivado desde el original el 3 de mayo de 2014. «occurs first in a pair of later papers by Zenneck (1899a,b)».