Sri Ramanananda Maharshi has written a lot of books on our beloved Shirdi SaiBaba.
Below is the list of books that Maharshiji has written:
1) Atma Darsana Anubuthi
2) Shaktipaatam
3) Shirdi Sai Anugraha Rahasyam
4) Shirdi Sai Seva Rahasyam
5) Parama Gurutho Sahajeevanam
Also as part of the 1 millions free book distribution a book named 'Shirdi Sai Anugraha Seva Rahasyam' which contains the contents of books listed above (from 1 to 4) is being distributed.