In what ways does a Sadguru accept service from devotees through literary works?

According to the preface of the Shri Sai Satcharita, a Sadguru accepts service from devotees through books in two distinct ways. The first method is when the Sadguru creates great spiritual works themselves, with examples like the Shri Dnyaneshwari or Shri Dasbodh being cited. The second method, as detailed in Chapter 0, involves the Sadguru having their biographies written by their devotees. The Sadguru then accepts service in the form of devotional study and 'Parayans' (systematic readings) of these biographies, not just from the author but from the entire congregation of devotees who engage with the text.