Correspondence: Marconi, Guglielmo. Letters to Josephine Bowen Holman
Correspondence: Marconi, Guglielmo. Letters to Helen Holman - Z; Ephemera
[Marconi, Guglielmo, 1874-1937]. Morse Code Legend ([undated)]
Josephine Bowen Holman. Diary (1902, January-April)