 For many years, Scarlatti's keyboard sonatas were conventionally identified by their Longo numbers, but these were later superseded by those found in Ralph Kirkpatrick's catalogue.Longo's Catalogue originated in his landmark full publication of the works of Scarlatti in 11 volumes and implied particular groupings of the sonatas, the chronology of which was later completely revised and differently grouped in Kirkpatrick's 1953 study of the composer.Longo also edited works by Domenico Gallo.