Stewart shot much of the footage for the Farrah's Story documentary, showing the Charlie's Angels favorite try and seek out new treatments in a bid to prolong her life.
And after the success of the documentary, which pulled in 8.9 million viewers in the U.S. when it was aired in May, Stewart will release My Journey With Farrah in August.
Some of the profits raised from sales of the book will go to the Farrah Fawcett Foundation for cancer research.
The actress died on June 25 at age 62.
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