Courtesy of David Pollak A Stone of Remembrance in the sidewalk of the Leopoldstadt neighborhood of Vienna. It’s embedded in front of the apartment building the author’s grandmother — Regine Wittman Pollak — lived in before she was taken to a Nazi death camp in 1942. My father, a Holocaust survivor who reached the United States in 1940 at age 29, never disclosed much about his life in Vienna or the time he spent afterward confined in Dachau and Buchenwald. What my sister and I did know was that he was one of three brothers who somehow managed to avoid...