Hordes more documentation:
https://read.cnu.edu/record=b1125761
https://read.cnu.edu/search~S0/?searchtype=c&searcharg=D804.19+.D63+1999
https://www.nationalarchives.gov.uk/education/resources/holocaust/
https://www.ushmm.org/antisemitism/holocaust-denial-and-distortion/evidence-documentation-holocaust
https://collections.arolsen-archives.org/
https://collections.arolsen-archives.org/en/archive/1-1-22
https://collections.arolsen-archives.org/en/archive/1-1-2
https://collections.arolsen-archives.org/en/archive/1-1-34-0_9004900
https://collections.arolsen-archives.org/en/archive/1-1-36
https://www.nsa.gov/portals/75/documents/about/cryptologic-heritage/historical-figures-publications/publications/wwii/eavesdropping.pdf