Secret Conversations with Hitler, which records his vehement hatred of Christianity, consists of confidential interviews given to Richard Breiting in 1931. Breiting was a member of the German People's Party. In these conversations, Hitler reveals his aims and plans. Like another book, Hitler's Table-Talk, the notes were taken in short-hand. Unlike the Table-Talk, which Hitler knew would later be revealed, Hitler was assured that his statements would be kept secret. [Calic, p.11] Moreover, the Secret Conversations were authenticated as written solely by Breiting (unlike the editing by Bormann).
Hitler's Secret Conversations is listed as a source by Encyclopedia Brittanica for Hitler's writings and speeches:
http://www.britannica.com/eb/article-215448
Hitler's Secret Conversation was used as a source by a History Channel documentary about Hitler:
http://www.thehistorychannel.co.uk/site/search/search.php?searchtext=hitler&refinetext=&search_page=3&themes=&cts=&enc=22201
The book is used as a source for research about Hitler in academic publications such as the Institute for Historical Review:
http://72.14.207.104/search?q=cache:BzQTJ1LA-uEJ:www.ihr.org/jhr/v04/v04p-93_Rollins.html+hitler%27s+secret+conversations&hl=en&gl=us&ct=clnk&cd=9
A single source? Not good. When were these conversations made public? Do you have any more info about this Breiting fellow?
For now I'll stick to analyzing his public quotes with multiple verifications before accepting single sourced quotes that completely counter them.
Like another book, Hitler's Table-Talk, the notes were taken in short-hand.
That is not a point of authentication.
Unlike the Table-Talk, which Hitler knew would later be revealed, Hitler was assured that his statements would be kept secret. [Calic, p.11]
This also is not a point of authentication.
Moreover, the Secret Conversations were authenticated as written solely by Breiting (unlike the editing by Bormann).
That just verifies a single source, and adds nothing to authentication.
Also, whether others use it as a legitimate source means nothing to me, unless I can analyse their reasonings for using it.