The Arolsen Archives only have copies of the number books from Buchenwald. Although some of the pages are difficult to read, it is possible to identify the prisoner numbers in the left-hand column. These are not always written out in full; instead, they each relate to the previous number. The prisoner’s first and last name were also recorded, as well as the block or sub-camp in which the prisoner was housed. Only pencil was supposed to be used to write in the number books so that prisoners who had been released, transferred or died could be erased and new names could be entered.