Between 1943 and 1944, some members of the Birkenau "Sonderkommando" were able to obtain writing materials and record some of their experiences and what they had witnessed. These documents were buried in the grounds of the crematoria and recovered after the war. Five men have been identified as the authors of these manuscripts: Zalman Gradowski, Zalman Lewental, and Leib Langfus, who wrote in Yiddish; Chaim Herman, who wrote in French; and Marcel Nadjary, who wrote in Greek. Of the five, only Nadjary survived until liberation; Gradowski was killed in the revolt at Crematorium IV on 7 October 1944 (see below), or in retaliation for it; Lewental, Langfus, and Herman are believed to have been killed in November 1944. Gradowski wrote the following note, found buried at an Auschwitz crematorium site: