Except for the last ebook, you can download all of them.
First 3 are in PDF format.
Next 2 are on google books, with an option to download in PDF format.
Last is for online reading only. Although if you are a hacker, that won't be any problem for you.
By C.V. Vaidya
Life of Shivaji Maharaj - Founder of Maratha Empire
By Krishnarao Arjun Keluskara, N.S. Takakhav
Siva Chhatrapati : being a translation of Sabhasad Bakhar with extracts from Chitnis and Sivadigvijya, with notes (1920)
By Surendranath Sen
Nana Phadnavis's Bakhar (Biography) in Marathi
By Capt A Macdonald.
Nana Phadnavis's Bakhar (Biography) in English
By Capt A Macdonald.
The Great Maratha - Mahadji Shinde
N. G. Rathod