In 1968, Berio completed "O King" a work which exists in two versions: one for voice, flute, clarinet, violin, cello and piano, the other for eight voices and orchestra. The piece is in memory of Martin Luther King Jr., who had been assassinated shortly before its composition. In it, the voice(s) intones first the vowels, and then the consonants which make up his name, only stringing them together to give his name in full in the final bars.The orchestral version of "O King" was, shortly after its completion, integrated into what is perhaps Berio's most famous work, "Sinfonia" (1967–69), for orchestra and eight amplified voices. The voices are not used in a traditional classical way; they frequently do not sing at all, but speak, whisper and shout. The third movement is a collage of literary and musical quotations. "A-Ronne" (1974) is similarly collaged, but with the focus more squarely on the voice. It was originally written as a radio program for five actors, and reworked in 1975 for eight vocalists and an optional keyboard part. The work is one of a number of collaborations with the poet Edoardo Sanguineti, who for this piece provided a text full of quotations from sources including the Bible, T. S. Eliot and Karl Marx.