Unfortunately, relatively little has been written about sacred and liturgical jazz. In a 2013 doctoral dissertation, Angelo Versace examined the development of sacred jazz in the 1950s using disciplines of musicology and history. He noted that the traditions of black gospel music and jazz were combined in the 1950s to produce a new genre, "sacred jazz." Versace maintained that the religious intent separates sacred from secular jazz. Most prominent in initiating the sacred jazz movement were pianist and composer Mary Lou Williams, known for her jazz masses in the 1950s and Duke Ellington. Prior to his death in 1974 in response to contacts from Grace Cathedral in San Francisco, Duke Ellington wrote three Sacred Concerts: 1965 - A Concert of Sacred Music; 1968 - Second Sacred Concert; 1973 - Third Sacred Concert.