There are some puzzling omissions--Mozart's Così fan tutte and Abduction from the Seraglio--and puzzling inclusions as well: Paderewski's Manru and Horatio Parker's Mona are not considered standard operas by any authority that readily springs to mind. Borodin's Prince Igor is, incomprehensibly, given in Italian and English (the Russian people improbably sing, "Ad Igor, signor nostro, vittoria"), as are Mussorgsky's Boris Godunov and Tchaikovsky's Evgeny Onegin. There are also some annoying little errors that could have been avoided with more careful proofreading ("Madam Butterfly"?), and the paper used is disappointingly cheap. Still, with these caveats in mind, The Book of 101 Opera Librettos is a very useful book for the money, a one-stop shop for many of the operas you're likely to encounter. Just be sure to read the libretto before you leave for the opera house.