Can you provide a summary of the significant Guru biographies mentioned in the text?

The preface discusses several important Guru biographies. Chapter 0 highlights two primary works: the Brihat or Thorale Guru Charitra by Shri Saraswati Gangadhar, and the Shri Sai Satcharita by Shri Annasaheb Dabholkar, which is the main subject of the preface. The text also mentions other biographies, including a scholarly one by Shri Samarth Sadguru Tembhe Swami and another by Shri Samarth Sadguru Dattatreya Maharaj that was not yet published. Additionally, two shorter but excellent biographies of Sai Baba by Shri Dasganu Maharaj are noted as appearing in his works Bhaktalilamrut and Bhaktisaramrut.