Along with his mentor Arnold Schoenberg and his colleague Alban Berg, Webern was in the core of those in the circle of the Second Viennese School, including Theodor W. Adorno, Heinrich Jalowetz, and Ernst Krenek. As an exponent of atonality and twelve-tone technique, Webern exerted influence on contemporaries Luigi Dallapiccola, Křenek, and even Schoenberg himself. As a tutor, Webern guided and variously influenced Arnold Elston, Frederick Dorian (Friederich Deutsch), Matty Niël [nl], Fré Focke [de], Karl Amadeus Hartmann, Philipp Herschkowitz, René Leibowitz, Humphrey Searle, Leopold Spinner, and Stefan Wolpe.