Question: Suvini Zerboni was the agent of which prolific german composer violist, violinist, teacher and conductor ?

Context articles: Due pezzi (Berio)
Heinrich Lichner
Donald Heins
Suvini Zerboni
Emil Kreuz
Eugenio Cavallini
Norbert Schultze
Cinque variazioni (Berio)
Paul Hindemith
Eduard Oja

Due pezzi, literally meaning "two pieces", is a composition for violin and piano, written by the Italian composer Luciano Berio in 1951.
 It was published by Suvini Zerboni.
 The first performance—by pianist Seymour Lipkin and violinist Lorin Maazel, to whom the work is dedicated—took place during the 1952 Tanglewood Music Festival.
 Berio composed these pieces and three other works ("Cinque variazioni" for piano, "Chamber Music" for female voice, clarinet, harp, and cello, and the Variations for chamber orchestra) in response to meeting Luigi Dallapiccola.
 As the composer says: "with these works I entered the 'melodic' world of Dallapiccola and these same works allowed me to leave it".
Heinrich Lichner (6 March 18297 January 1898) was a prolific German composer, best known today for his teaching pieces - simple piano works written for students.
 He was born in Harpersdorf, Silesia.
 His sonatinas, including Opp.
 4, 49, and 66 (among others) are in a light, fluent classical style, although the harmony occasionally betrays the influence of romanticism.
 He was also a director and organist - he worked as organist at the church of the 11,000 virgins, and spent a part of his life as the director of a "saengerbund" (choral festival) in Breslau, where he died.
Donald Heins (19 February 1878 – 1 January 1949) was a Canadian violinist, violist, conductor, organist, composer, and music educator of English birth.
 He notably founded the first professional orchestra in Ottawa, the Ottawa Symphony Orchestra (no relation to the current orchestra of that name), in 1902, serving as its director until 1927.
 He also served in a variety of positions with the Toronto Symphony Orchestra from 1927–1949, including concertmaster, principal violist, and assistant conductor.
Suvini Zerboni (ESZ) Italian music publishing house founded in 1907 in Milan, taking its name from the theater society of the same name.
 The ESZ catalogue included, besides operetta favourites, the best of Italian contemporary music, such composers as Goffredo Petrassi, Luigi Dallapiccola, Luciano Berio, Ildebrando Pizzetti, and Gian Francesco Malipiero.
 Since the 1950s, ESZ has been the Italian agent of Schott Music, representing composers such as Igor Stravinsky, Carl Orff, Paul Hindemith, Richard Strauss, Luigi Nono, Krzysztof Penderecki and Joaquín Rodrigo.
 The ESZ catalalogue of modern Italian composers active since the 1970s is extensive.
 ESZ also publishes the bulletin “ESZ News” with information on the activities and performances of its composers.
 Until 1999 ESZ published "Il Fronimo", the guitar magazine founded by Ruggero Chiesa in 1972, and "La Cartellina", a magazine on choral and pedagogical music, founded by Roberto Goitre in 1977 and subsequently headed by Giovanni Acciai.
Emil Anton Joseph Friedrich Kreuz, also known as Emil Frederick Thornfield, (25 May 1867 in Elberfeld – 3 December 1932 in London) was a German violinist, violist, teacher, conductor and composer.
Eugenio Cavallini (16 June 1806 — 11 April 1881) was an Italian conductor, composer, violinist, and violist.
 In 1833 he became first violinist of the orchestra at La Scala, a post he held through 1855.
 He also served as a conductor at La Scala, notably leading the world premieres of Gaetano Donizetti's "Lucrezia Borgia" (1833), Donizetti's "Gemma di Vergy" (1834), Donizetti's "Maria Stuarda" (1835), Saverio Mercadante's "Il giuramento" (1837), Mercadante's "Il bravo" (1839), Giuseppe Verdi's "Oberto" (1839), Verdi's "Un giorno di regno" (1840), Donizetti's "Maria Padilla" (1841), Verdi's "Nabucco" (1842), Verdi's "I Lombardi alla prima crociata" (1843), Verdi's "Giovanna d'Arco" (1845), Federico Ricci's "Estella di Murcia" (1846), and Domenico Ronzani's "Salvator Rosa" (1854).
Norbert Arnold Wilhelm Richard Schultze (26 January 1911 in Brunswick – 14 October 2002 in Bad Tolz) was a prolific German composer of film music.
 He is best remembered for having written the melody of the World War II classic "Lili Marleen", originally a poem from the 1915 book "Die kleine Hafenorgel" by Hans Leip.
Cinque variazioni ("Five variations") is a composition for solo piano by Luciano Berio, written in 1952/3 and greatly revised in 1966.
 It was published by Suvini Zerboni and the first performance was given by Berio in Milan in 1953.
 The variations are based on a three-note melodic cell—""fratello""[014]—from the opera "Il prigioniero" by Luigi Dallapiccola, to whom the work is dedicated .
 Major changes between the two versions are indicated below, but many other small changes may be found, mostly additions to render the harmony more complex.
Paul Hindemith ( ) (16 November 1895 – 28 December 1963) was a prolific German composer, violist, violinist, teacher and conductor.
 Notable compositions include his song cycle "Das Marienleben" (1923), "Der Schwanendreher" for viola and orchestra (1935), and opera "Mathis der Maler" (1938).
 Hindemith's most popular work, both on record and in the concert hall, is likely the "Symphonic Metamorphosis of Themes by Carl Maria von Weber", written in 1943.
Eduard Oja (January 17, 1905 in Palupõhja - April 16, 1950 in Tartu) was an Estonian composer, conductor, music teacher and critic.
 His father was a forest warden.
 Between 1919-1925 he studied at Tartu Teacher's College at Tartu University, where he met Eduard Tubin, and he also worked for some time as a school teacher.
 He was not a particularly prolific composer, composing mainly orchestral and ensemble works and choral music.
 He was however much appreciated during his lifetime, and received awards and acclaim for several of his works.
 He also worked as a conductor, leading the Tartu Women's Singing Society’s Women's Choir between 1930 and 1934, as well as a teacher of music theory at Tartu Higher School of Music.
 In addition, he was himself a practising violinist.
 A number of his works such as the opera Oath Redeemed (Estonian: "Lunastatud vanne" ) and the choral work The Return Home (Estonian: "Kojuminek" ) have been lost, although the majority of his work has survived, and is valued in museums in Estonia today.
 The Eduard Tubin Museum of Alatskivi Castle contains exhibits related to him and his fellow students under Heino Eller, known as the "Tartu school", such as Eduard Tubin, Alfred Karindi, Olav Roots and Karl Leichter.