A couple of years later, William Friedkin contacted Blatty to turn it into a film, and Blatty wrote the script.

Source: https://screenrant.com/exorcist-movie-true-story-regan-roland-doe-explained/

A few of them – Francis Ford Coppola, Peter Bogdanovich, William Friedkin – even tried to start American arthouse studio in San Francisco in the early 1970s, making their movies far away from the studio executives.

Source: https://thenewdaily.com.au/entertainment/movies/2023/08/08/william-friedkin-cinema-legacy/

Director William Friedkin most famously depicted the devil in the 1973 movie scaring audiences to the extent it caused “fainting, vomiting and heart attacks in cinemas”.

Source: https://thenewdaily.com.au/entertainment/2023/04/05/russell-crowe-the-popes-exorcist/

Director William Friedkin wasn’t happy with the soundtrack until he found the perfect song by accident.

Source: https://collider.com/the-exorcist-theme-song-tubular-bells/

In this cut, director William Friedkin reinserted the bloody version of the spider walk, using CGI to erase the wires, and remastering the footage to fit with the rest of the film, much to Blatty's delight.

Source: https://screenrant.com/exorcist-movie-regan-spider-walk-scene-deleted-restored-why/

“William Friedkin was my first friend among the filmmakers of my generation and I grieve for the loss of a much-loved companion,” five-time Oscar winner Coppola wrote.

Source: https://deadline.com/2023/08/william-friedkin-death-francis-ford-coppola-tribute-1235457042/