Musicologist Ewen has made an attempt to define the boundary between "light opera" and musical comedies, musical plays, and grand opera. He has focussed on the standards of Viennese operates, French opera-comique and opera-bouffe, English comic and romantic opera, and italian opera-buffa, including a limited number of other works (such as Martha) in his opinion "so ingratiating in manner and so readily assimilable by audiences at first hearing" that they belong in a full treatment of the field. Using an average of five paragraphs each, he covers 167 European works by 81 composers, written between 1728 and 1949. Production history, plot, points of significant musical interest, are given, set off by fragments of critical evaluation. the plan of the book is alphabetical by little of work, with appropriate cross-titling for transitions. Ewen's customary reckless use of the words "masterwork"and"masterpiece" is the only serious shortcoming of an otherwise straightforward reference book. americans, semi professional producers will find this a useful work of comprehensive, but manageable, proportions. (Kirkus Reviews)