Besides the Shri Sai Satcharita, what other major Guru biography is mentioned as being widely studied?

The preface in Chapter 0 identifies another major Guru biography that is widely studied, known as the Brihat or Thorale Guru Charitra. This work, written by Shri Saraswati Gangadhar, chronicles the lives of Shri Guru Dattatreya and his incarnations. It is described as being well known to both young and old and is used for daily study and Parayans in thousands of locations. The text positions this work and the Shri Sai Satcharita as the two most detailed Guru biographies of their kind.