引用・参考文献等 https://www.quora.com/Why-didnt-the-U-S-use-the-B-29-on-the-European-Fronthttps://www.quora.com/Why-were-B-29s-never-used-in-the-European-theater-against-the-Germans
http://www.nicovideo.jp/watch/sm46551338
