Lewis C. Strang - Celebrated Comedians of Light Opera and Musical Comedy in America (1900)
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Strang (1869–1935) wrote several books about stage performers including Famous Actors of the Day, Famous Actresses of the Day, Famous Prima Donnas, Players and Plays of the Last Quarter Century. Clearly not engaged criticism but invaluable source material. And in fact I find many references to his books but little about the person. He was from the Boston area and started writing there but I can't tell if that's where he remained, whether he published only books or much else. This book was reprinted in 1906 as Famous Stars of Light Opera.