Agon (1954–57) was the first of his works to include a twelve-tone series and Canticum Sacrum (1955) was the first piece to contain a movement entirely based on a tone row.
Agon (1954–57) foi a primeira das súas obras que incluiu series dodecafónicas, e Canticum Sacrum (1955) foi a primeira peza que contivo un movemento enteiramente baseado nun tono fila.