In this A-H sequel to v. 21 (1986), Parsons, who has been involved in virtually every facet of opera production and research, catalogues opera scores maintained in US libraries by composer through their melodious from 19th century Pietro Abba-Cornaglia's Una Partita a scacchi (1892) to John Harbison's Full Moon in March (1977). Entry arrangement is composer, title, publication data (the year is the least reliable information), music number, series, type of score, and type of reproduction. No index. Annotation c. by Book News, Inc., Portland, Or.