 Complete the following phrase:  Rachel Zylberberg was born Rachela Zylberberg on 5 January 1920 in Warsaw, interwar Poland, to Orthodox Jewish parents: Alexander Sender and Masha née Nordwind. Her parents owned a dairy-goods store at 37 Nowolipki Street, and later at 40a Nowolipki. Rachela Zylberberg studied at the Jewish Gymnasia and joined Hashomer Hatzair, where she became member of the Frontline Brigade eventually, along with Mordechai Anielewicz, Commander of the Warsaw Ghetto Uprising. While in school, she excelled at her studies, excelled also at sports, and was known for her strong organizational abilities. As of 1938, she became a group leader for the younger students who greatly admired her. She received her matriculation certificate just as the Second World War broke out on 1 September 1939 with the German invasion of Poland. Two weeks later, 