Josef Zelkowicz (1897.1944) was born to an affluent hassidic family in Konstantynow, near Lodz. He acquired a broad Jewish and general education. In 1929, he joined the staff of the YIVO (lnstitute for Jewish Research) branch in Lodz, researched the Yiddish language and Jewish folklore, and began to publish articles on these topics in the Yiddish press in Lodz and abroad. By the winter of 1940, the Jews of Lodz had been forced into a sealed ghetto under extremely harsh conditions. Even there, Zelkowicz continued his cultural and literary activities. His most important work involved the documentation of ghetto life. He was a mainstay of the ghetto archives that began to operate in November I 940 and was a principal author of the daily ghetto chronicle that lasted from January 1941 to late July 1944. During that time, Zelkowicz wrote nearly 50 articles on a wide variety of themes related to ghetto life these works were later incorporated into the ghetto archives. He also kept a personal diary. In Those Terrible Days includes only a small selection of his work. Zelkowicz'S writings shed important historical light on the Lodz ghetto . the second - largest Jewish ghetto created by the Nazis and the last to be liquidated . especially in regard to daily life and individuals' struggle for survival. When the Lodz ghetto was liquidated in August 1944, Josef Zelkowicz was deported to Auschwitz, where he was murdered. Several hundred Jews were left behind to clean up the empty ghetto. One of them, Nachman Zonabend, seized a never - .to - .recur opportunity to remove and conceal a large amount of documentation from the archives, including much of ZelkowiczS work. After the war, Zonabend managed to remove some of the original materiai from Poland and donated it to the YIVO archives in New York, the Yad Vashem Archives, and the archives of the Ghetto Fighters' House.