It seems that in the context of the rather recent book, another book, should be mentioned. This is "Aikido in America
", Stone John and Meyer Ron eds., 1995, Frog, Ltd. Berkley, California.
In their book, the editors bring several interesting interviews with many Aikido pioneers that contributed to the dissemination of Aikido in the US. Among them are the several American Aikido practitioners, that were privileged to study in Japan when the O-sensei was still alive and teaching. Of special interest are the interviews with Terry Dobson and Mary Heiny. Also included in the book are interviews with some of the early American Aikido practitioners that describe the early days of Aikido in the US (Frank Doran and Wendy Palmer, for example).
For people interested in the early days of Aikido in the US, it's a very interesting and worthwhile reading.