A death register (Sterbebuch) in the Auschwitz Museum's preservation laboratory for documents, books and other historical papers. 51 death registers have been preserved. It takes three to four staff approximately three months work to preserve each volume. It is estimated that between 1.1 and 1.5 million Jews, Poles, Roma and others were killed in Auschwitz-Birkenau during the Holocaust between 1940-1945. 27 January 2015 is the 70th anniversary of the liberation of Auschwitz-Birkenau.