The preface mentions several Guru biographies. Can you elaborate on the ones that were less known or not widely published?

The preface, as detailed in Chapter 0, touches upon several Guru biographies that were not as prominent as the Shri Sai Satcharita. One such work was written by Shri Samarth Sadguru Tembhe Swami, also known as Vasudevanand Saraswati Maharaj. This biography is described as detailed and scholarly, but it had not become as famous as the one by Shri Saraswati Gangadhar. Additionally, the author mentions hearing of a Guru biography by Shri Samarth Sadguru Dattatreya Maharaj of Balekundri, but notes that it did not appear to have been printed or published at that time.