Can you elaborate on the two forms of service a Sadguru accepts from devotees through literary works?

Chapter 0 outlines two distinct ways a Sadguru takes service from devotees through books. The first method is when the Sadguru creates great works themselves, with examples like Shri Dnyaneshwari or Shri Dasbodh. The second method, which is relevant to Sai Baba, is when the Sadguru has his biographies written through his devotees. He then accepts service from the writer and the wider congregation of devotees who engage in the study and Parayans of these biographical works, such as the Shri Sai Satcharita. This fosters a community dedicated to studying the Guru's life and teachings.