Electronic reproduction. [Place of publication not identified] : HathiTrust Digital Library, 2010.
Master and use copy. Digital master created according to Benchmark for Faithful Digital Reproductions of Monographs and Serials, Version 1. Digital Library Federation, December 2002. http://purl.oclc.org/DLF/benchrepro0212
Volumes for 1936-39 include summaries in German. 1940-19; summaries in French. Summaries subsequently in English or German.