The preface mentions several Guru biographies. Which ones are considered the most detailed and famous?

The text identifies two Guru biographies as being exceptionally detailed and well-known. The first is the ancient 'Brihat Guru Charitra' by Shri Saraswati Gangadhar, which is described as being studied daily in thousands of places. The second is the more recent 'Shri Sai Satcharita,' written by Annasaheb Dabholkar about Sai Baba. The preface, as detailed in Chapter 0, explicitly states that 'no third work written in such detail is found,' underscoring the unique significance and comprehensiveness of these two particular biographies in the landscape of Guru literature.