See the sentence on the last page (p.641) of the original edition of Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig? in Annalen der Physik, 1905, below the equation K0 - K1= L/V2 v2/2. See also the sentence under the last equation in the English translation, K0 - K1= 1/2 L/c2 v2, and the comment on the symbols used in About this edition that follows the translation [1]
See the sentence on the last page (p.641) of the original edition of Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig? in Annalen der Physik, 1905, above the equation K0 - K1= L/V2 v2/2. See also the sentence above the last equation in the English translation, K0 - K1= 1/2 L/c2 v2, and the comment on the symbols used in About this edition that follows the translation [2]
questia.com
M.C.Shields Bibliography of the Writings of Albert Einstein to May 1951 in Albert Einstein: Philosopher-Scientist by Paul Arthur Schilpp (Editor) Albert Einstein Philospher - Scientist
stanford.edu
plato.stanford.edu
In F. Fernflores. The Equivalence of Mass and Energy. Stanford Encyclopedia of Philosophy. [3]
