Elementare Betrachtungen über die thermische Molekularbewegung in festen Körpern, Albert Einstein
[in] Annalen der Physik, Vierte Folge, Band 35, Heft 4
First edition of Einstein's sequel and complement to his 1907 paper on Planck's theory of radiation and heat, translated as Elementary Observations on Thermal Molecular Motion in Solids. Recognizing that his model of specific heats is incorrect at very low temperatures, Einstein tries to improve it. The correct answer would come a year later with the Debye model.
Leipzig: Verlag von Johann Ambrosius Barth, 1911. Whole issue, disbound from larger volume but still stiched together, front wrapper detached, pp. 617-816 + 3 plates. Front wrapper chipped with loss and tears, else very good. Uncommon in this format.