Bohr (Niels) On The Quantum Theory of Line Spectra, 3 parts, first edition, part 1 presentation copy inscribed by the author on upper cover, offprints from Memoires de l'Academie Royale des Sciences et des Lettres de Danemark, original printed wrappers with "Separate Copy" in upper left corner of each front cover, very slightly toned and chipped, preserved together in modern cloth drop-back box with small leather book-label of Haven O'More, 4to, Copenhagen, 1918-22.

⁂ Rare in such condition and with an autograph presentation inscription, here to Kasimir Fajans. One of Bohr's most important papers and the basis for Bohr's Nobel Prize. These papers give the first clear formulation of his 'correspondence principle' establishing the limit agreement of quantum and classical physics.