composers, such as Mikhail Glinka, Alexander Serov, Rimsky-Korsakov, Puccini and Mascagni wrote passages of music without text and subsequently had the librettist add words to the vocal melody lines. (This has often been the case with American popular song and musicals in the 20th century, as with Richard Rodgers and Lorenz Hart's collaboration, although with the later team of Rodgers and Hammerstein the lyrics were generally written first, which was Rodgers' preferred modus operandi.) Some composers wrote their own libretti. Richard Wagner is perhaps most famous in this regard, with his transformations of Germanic legends and events into epic subjects for his operas and music dramas. Hector Berlioz, too, wrote the libretti for two of his best-known works, La damnation de Faust and Les Troyens. Alban Berg adapted Georg Büchner's play Woyzeck for the libretto of Wozzeck. Sometimes the libretto is written in close collaboration with the composer; this can involve adaptation, as was the case with Rimsky-Korsakov and his librettist Vladimir Belsky, or an entirely original work. In the case of musicals, the music, the lyrics and the "book" (i.e., the spoken dialogue and the stage directions) may each have its own author. Thus, a musical such as Fiddler on the Roof has a composer (Jerry Bock), a lyricist (Sheldon Harnick) and the writer of the "book" (Joseph Stein). In rare cases, the composer writes everything except the dance arrangements – music, lyrics and libretto, as Lionel Bart did for Oliver!. Other matters in the process of developing a libretto parallel those of spoken dramas for stage or screen. There are the preliminary steps of selecting or suggesting a subject and developing a sketch of the action in the form of a scenario, as well as revisions that might come about when the work is in production, as with out-of-town tryouts for Broadway musicals, or changes made for a specific local audience. A famous case of the latter is Wagner's 1861 revision of the original 1845 Dresden version of his opera Tannhäuser for Paris. Literary characteristics The opera libretto from its inception (ca. 1600) was written in verse, and this continued well into the 19th century, although genres of musical theatre with spoken dialogue have typically alternated verse in the musical numbers with spoken prose. Since the late 19th century some opera composers have written music to prose or free verse libretti. Much of the recitatives of George Gershwin's