What kind of sources used. You allude to the fact access in china is difficult these days. What kind of sources did you use . Second question, what do you was the most challenging thing about writing the biography . Putting this book together was a real effective story. You know, there are some of the different pieces to it, different aspects to it. As i mentioned before i was very fortunate to meet three of birches surviving brothers, papers of William Dolan at uc berkeley, papers of the wedemeyer at the hoover institution. The 14th air force archive at montgomery, alabama, Maxwell Air Force base, socially and exciting trip, and exciting find because buried in those materials is a 24, 25 page interview, oral history interview with john birch which was conducted about five months before his death. The Army Air Force historian arranged this interview because of john birch was the first of these field intelligence officers. He had met doolittle. He had led a colorful life, so theres some