Astronomy for Amateurs
1925
Mysterious Psychic Forces: An Account of the Author's Investigations in Psychic…
1925
Astronomical Myths: Based on Flammarions's "History of the Heavens"
1906
Thunder and Lightning
1925
Urania
1925
Lumen
1925
Dreams of an astronomer
1925
Uranie
1925
Omega: The Last days of the World
1925
De Wereld vóór de schepping van den mensch
1925
Komet und Erde: Eine astronomische Erzählung
1925