source
Aage Petersen, [http://books.google.com/books?id=DgcAAAAAMBAJ&lpg=PA36&pg=PA8 "The philosophy of Niels Bohr"] by in the Bulletin of the Atomic Scientists Vol. 19, No. 7 (September 1963); The Genius of Science: A Portrait Gallery (2000) by Abraham Pais, p.