Rudy Shackleford has pointed out that in my (English) monograph Luigi Dallapiccola, published in 1957, I gave two different forms of the series on which Luigi Dallapiccola's Quaderno Musicale di Annalibera is based: a first, ‘erroneous’ form (quoted in Shackleford's Example Ia), and a second one, included in the ‘arc of melody’ in piece No. 6 of the Quaderno, ‘Fregi’. This second form, quoted in Shackelford's Ex. No. Ib (which is obviously the ‘right’ one) differs from the first in the placing of two notes — G and A. Shackleford's remark requires some clarification, not so much for personal reasons as for its bearing on the very nature of the 12-note method and serial writing.