English and Danish.

v. 6- : General editor, Erik Rudinger.

v. 1-5: Sole distributors for the U.S.A. and Canada: American Elsevier Pub. Co., New York, N.Y.; v. 6- : Sole distributors for the U.S.A. and Canada: Elsevier Science Pub. Co., New York, N.Y.

Includes bibliographical references and indexes.

v. 1. Early work (1905-1911), edited by J. Rud Nielsen. --v. 3. The correspondence principle (1918-1923), edited by J. Rud Nielden.--v. 4. The periodic system (1920-1923).--v. 5. The emergence of quantum mechanics (mainly 1924-1926), edited by Klaus Stolzenburg.--v. 6. Foundations of quantum physics I (1926-1932), edited by Jorgen Kalckar. --v. 8. The penetration of charged particles through matter (1912-1954), edited by Jens Thorsen.