Best biography of rasputin

Grigori Yefimovich Rasputin[n 1] (21 January [O.S. 9 January] – 30 December [O.S. 17 December] ) was a Russian mystic and faith healer. He is best known for having befriended the imperial family of Nicholas II, the last Emperor of Russia, through whom he gained considerable influence in the final years of the Russian Empire. Grigori Rasputin, Siberian peasant and mystic whose ability to improve the condition of Aleksey Nikolayevich, the hemophiliac heir to the Russian throne, made him a favorite at the court of Emperor Nicholas II and Empress Alexandra. Rasputin reached the pinnacle of his power at the Russian court after Early years First steps Professional growth Public recognition Peak period Later years Public interest Professional activity Media attention
Hey guys, I've always been fascinated by Rasputin, and I've read a few books about him written in Spanish already. I believe him to be one of the most interesting characters of history. What are the best biographical books I can read about him in English (recommendations in Spanish/Portuguese also fine)? I'm particularly interested in his ability as an individual to cure haemophilia, his.