Research the historical period in which the work was written.
United States Holocaust Memorial Museum - in Washington D.C. has first person and historical information on the Holocaust. Very comprehensive. Look at the Resources for Academics link under the menu; if you have a question, you can ask a research question of a librarian at the museum. https://www.ushmm.org/
Los Angeles Museum of the Holocaust - has first person and historical information; there is a virtual tour link of the museum. (If you go, it is very interactive, and in certain sections, tries to have you experience some of the feelings the inmates may have felt.) http://www.lamoth.org/
Museum of Jewish Heritage in New York has numerous exhibits about the Holocaust and primary sources online https://mjhnyc.org/