What is described as the most certain and effective form of written service for achieving salvation?

As detailed in Chapter 0, the best and most certain form of written service for attaining the fruit of salvation is to write the biography of one's own Sadguru. This act should be undertaken either by the Guru's direct command or through inner inspiration. It must be done with a pure heart, firm resolve, excellent faith, selfless love, and unwavering devotion. Furthermore, this service extends to personally studying the work, performing regular readings (Parayans) and weekly recitations (Saptahs), and encouraging other devotees to do the same.