The claim that the author was from East Berlin is found quite often in English reviews of or discussions about the book, so I feel I should correct it: At the time the diary was written there was no "East" Berlin, it was simply Berlin occupied by Soviet forces. The four sectors didn't exist until later that year. Also, the author did not live in what later on became East Berlin, she lived in Berlin-Tempelhof (American sector) until 1948 and in Berlin-Zehlendorf until 1955 when she married and moved to Switzerland.
Concerning the often disputed authenticity of the diary, during my research for its author's biography (ISBN 978-3-7322-4506-2, in German only) I found that the facts were largely correct, though many details had been changed in an effort to keep the anonymity of the mentioned persons intact. And yes, the author spoke some Russian, as she had lived and worked in the Soviet Union for two years. Regards, C. Schnabel