The text mentions several Guru biographies. Which ones are described as being less famous, unpublished, or distinct from the main ones?

The preface in Chapter 0 highlights several biographies that are not as prominent as others. It mentions a scholarly work by Shri Samarth Sadguru Tembhe Swami (Vasudevanand Saraswati Maharaj) but notes it does not seem to be as famous as the one by Saraswati Gangadhar. It also mentions hearing about a biography by Shri Samarth Sadguru Dattatreya Maharaj of Balekundri that had not yet been printed or published. Finally, it notes that the biography by Vasudevanand Saraswati Maharaj is in a different category because it was written by the Maharaj himself.