At first glance, the letter carefully printed in a child's hand seems innocuous, nothing more than the expression of a young crush: "I love you so much. Write me — please. Many greetings. Your Gina." But the note takes on a more sinister tone when its recipient is known: Adolf Hitler.

The 1935 letter is one of 300 in a new book "Briefe An Hitler" — "Letters to Hitler" — by German historian Henrik Eberleby. He examined more than 20,000 letters in Russian archives. The letters give a unique glimpse into the minds of Germans during the Nazi era, from party sycophants and ordinary citizens to political opponents and Jews suffering under the Nazi regime.

Eberle stumbled on the letters when researching an earlier book on Hitler.

"It is important to show the whole picture," he said. "There are totally normal people's feelings, and then there are also the thoughts of the prominent people."

The Nazis kept meticulous records, and the letters had been carefully stored in Berlin. They were seized by the Soviet army at the end of World War II and taken to Moscow.

While some individual letters have been previously published — like one from World War I hero Gen. Erich Ludendorff complaining of diminishing freedoms under the Nazis — the vast majority have never been seen by the public.

"It was known that there was this archive, it was known it was available to be seen, but there hasn't been a book that's brought them all together," Eberle said.

The 476-page book, which is being presented this week at the Frankfurt International Book Fair, is only available in German. Publishers Gustav Luebbe GmbH & Co. said there are no immediate plans for an English edition.

The letters illuminate the German zeitgeist from 1925 — the year Hitler published "Mein Kampf" detailing his ideology and ambitions — to 1945, when he ended his own life in a Berlin bunker.

Early letters were generally expressions of solidarity with the Nazi program and questions about Hitler's views, Eberle said.