Task: Question Answering
Input (English): Passage: Zappa's relationship with long-time manager Herb Cohen ended in 1976. Zappa sued Cohen for skimming more than he was allocated from DiscReet Records, as well as for signing acts of which Zappa did not approve. Cohen filed a lawsuit against Zappa in return, which froze the money Zappa and Cohen had gained from an out-of-court settlement with MGM over the rights of the early Mothers of Invention recordings. It also prevented Zappa having access to any of his previously recorded material during the trials. Zappa therefore took his personal master copies of the rock-oriented Zoot Allures (1976) directly to Warner Bros., thereby bypassing DiscReet.In the mid-1970s Zappa prepared material for Läther (pronounced "leather"), a four-LP project. Läther encapsulated all the aspects of Zappa's musical styles—rock tunes, orchestral works, complex instrumentals, and Zappa's own trademark distortion-drenched guitar solos. Wary of a quadruple-LP, Warner Bros. Records refused to release it. Zappa managed to get an agreement with Phonogram Inc., and test pressings were made targeted at a Halloween 1977 release, but Warner Bros. prevented the release by claiming rights over the material. Zappa responded by appearing on the Pasadena, California radio station KROQ, allowing them to broadcast Läther and encouraging listeners to make their own tape recordings. A lawsuit between Zappa and Warner Bros. followed, during which no Zappa material was released for more than a year. Eventually, Warner Bros. issued different versions of much of the Läther material in 1978 and 1979 as four individual albums (five full-length LPs) with limited promotion.Although Zappa eventually gained the rights to all his material created under the MGM and Warner Bros. contracts, the various lawsuits meant that for a period Zappa's only income came from touring, which he therefore did extensively in 1975–77 with relatively small, mainly rock-oriented, bands. Drummer Terry Bozzio became a regular band member, Napoleon Murphy Brock stayed on for a while, and original Mothers of Invention bassist Roy Estrada joined. Among other musicians were bassist Patrick O'Hearn, singer-guitarist Ray White and keyboardist/violinist Eddie Jobson. In December 1976, Zappa appeared as a featured musical guest on the NBC television show Saturday Night Live. Zappa's song "I'm the Slime" was performed with a voice-over by SNL booth announcer Don Pardo, who also introduced "Peaches En Regalia" on the same airing. In 1978, Zappa served both as host and musical act on the show, and as an actor in various sketches. The performances included an impromptu musical collaboration with cast member John Belushi during the instrumental piece "The Purple Lagoon". Belushi appeared as his Samurai Futaba character playing the tenor sax with Zappa conducting. 
Question: What is the last name of the person whose LP Warner Brothers refused to release?
Output (English): Zappa.