What are some ways to offer service to a Sadguru like Sai Baba through books and literature?

According to the preface in Chapter 0, a Sadguru accepts two primary types of service from devotees through books. The first is when the Guru creates great works themselves, like the Shri Dnyaneshwari. The second, more common way for devotees to serve is by having the Guru's biographies written through them. Devotees can then offer service in the form of study and performing Parayans, or devotional readings, of these biographies. This allows both the writer and the congregation of devotees to engage in a profound form of service and achieve the purpose of their lives.