In what ways can a devotee perform service to a Sadguru through books, as explained in the context of Sai Baba?

Chapter 0 outlines two principal methods by which a Sadguru accepts service from devotees through books. The first is when the Guru themselves authors a great work. The second method, which applies to Sai Baba, is when the Guru has their biography written by a devotee. Service is then accepted in the form of study and 'Parayans' from both the writer and the wider congregation of devotees. The text positions the 'Shri Sai Satcharita' as the vehicle for this service. By studying this work, devotees are not just learning about Sai Baba's life but are actively performing a service that the Sadguru accepts, thereby deepening their connection and devotion.