 Untersuchungen über die radioaktiven Substanzen by Marie Curie

By Marie Curie; translated with bibliographical supplements by Walter Kaufmann. Third unchanged German edition, Friedrich Vieweg und Sohn, Braunschweig, 1904; French thesis, 1903.

Cited passage: chapter I(b), measurement of radiation intensity, Figures 1–3. Gutenberg release 2011 and update 2020 are digitization dates.