doctoral dissertation by Leopold Infeld

scientific article published in 1934

1958 Czech book edition, second edition

1945 Czech book edition

1958 Czech book edition, third edition

scholarly article by Albert Einstein & Leopold Infeld published 1 June 1949 in Canadian Journal of Mathematics

literary work by Albert Einstein and Leopold Infeld

scientific article

Article from 'Scientific American', published in October 1949

Article from 'Scientific American', published in November 1949

scientific article published on 01 December 1949