Bujinkan practitioners sometimes refer to a book titled Kakutogi no Rekishi in an effort to support the historical provenance of various ryuha within the system. Unfortunately, the actual text is very difficult to find, and many references one finds online are erroneous. The "Bujinkan" Wikipedia article (as of 07/20/11) is particularly vexing in this regard.
Thanks to Harvard's Widener Library and the Waseda University Library, I was able to borrow the text for a short time. The book is often mistakenly said to have been published in 1843; this is not the case. The 1843 publication date is an attractive error, because pre-Takamatsu third-party BJK ryuha references seem to be very rare... I (foolishly!) didn't scan the copyright information when I had the book, but two friends have corroborated the publication date, and have kindly sent me a photo of the publication information page.
While I had the book, I scanned the pages containing the text most frequently referenced. JPEG images (and a PDF; PDF file does not yet include publication page) can be found below. The image name is the book's page number(s). The PDF file is a lower-resolution compilation of pages 508-518.