Question: Which artistic profession do Henry Koster and David Siegel share?

Context articles: Henry Koster
David Siegel (executive)
Catherine the Last
David Siegel (screenwriter)
The Great Opportunity
It Started with Eve
Versailles house
The Affairs of Maupassant
AMS Euler
Thea Roland

Henry Koster (born Hermann Kosterlitz, May 1, 1905 – September 21, 1988) was a German-born film director.
 He was the husband of actress Peggy Moran.
David Siegel ( ) is the current CEO of Investopedia.
 In the past, he served as the President of SeekingAlpha and a Senior Vice President for 1-800 Flowers.
 Siegel has earned both a BA in Philosophy, Politics and Economics and an MBA in Finance and Marketing, both degrees from the University of Pennsylvania.
Catherine the Last (German: Katharina, die Letzte) is a 1936 Austrian romantic comedy film directed by Henry Koster and starring Franciska Gaal, Hans Holt and Hans Olden.
 It was made by the Austrian subsidiary of Universal Pictures.
 After making the film Koster moved to Hollywood.
 In 1938 the film was remade in America as "The Girl Downstairs" with Gaal reprising her role.
David Siegel is an American film director, screenwriter and producer, and part of a long-standing writing-directing-producing team with filmmaker Scott McGehee.
The Great Opportunity (German:Die große Gelegenheit) is a 1925 German silent film directed by Lorand von Kabdebo and starring Kurt Vespermann, Lia Eibenschütz and Colette Brettel.
 The production is notable as marking the filmmaking debut of Henry Koster, who co-wrote the screenplay.
 Koster would go on to become a top Hollywood film director.
It Started with Eve is a 1941 American musical romantic comedy film directed by Henry Koster and starring Deanna Durbin, Robert Cummings, and Charles Laughton.
 The film received an Academy Award nomination for Best Original Music Score (Charles Previn and Hans J. Salter).
 The film is considered by some critics to be Durbin's best film, and the last in which she worked with the producer (Joe Pasternak) and director (Henry Koster) that groomed her for stardom.
 "It Started with Eve" was remade in 1964 as "I'd Rather Be Rich".
Versailles is a 90,000 square-foot house belonging to Westgate Resorts founder David Siegel and his wife Jackie Siegel — and under construction at 6121 Kirkstone Lane, Windermere, Florida, in the gated community of Lake Butler Sound in Orange County.
 USA.
 Named and modeled after the Palace of Versailles in France, the completed project will be one of the largest single-family homes in the United States.
The Affairs of Maupassant is a 1935 Austrian-Italian drama film production.
 The German title is "Das Tagebuch der Geliebten" and the Italian title is "Il diario di una donna amata", which means "the diary of a woman in love".
 An historical romance, it was directed by Henry Koster under his original name of Hermann Kosterlitz and starred Isa Miranda as the Ukrainian artist and diarist Marie Bashkirtseff and Hans Jaray as the French writer Guy de Maupassant.
 It was loosely based on Bashkirtseff's diaries, in which she records her studies in Paris to become an artist towards the end of the 19th century, and possibly on her correspondence with Maupassant, which she had begun under an assumed name.
 The film focuses on a feud between Maupassant and one of Bashkirtseff's teachers that leads to a nascent (and highly fictionalized) romance between Bashkirtseff and Maupassant.
 The romance is cut short in the film by Bashkirtseff's early death from tuberculosis.
 The film was made just before Koster moved to the United States to join Universal Studios.
 It was filmed in Vienna.
AMS Euler is an upright cursive typeface, commissioned by the American Mathematical Society (AMS) and designed and created by Hermann Zapf with the assistance of Donald Knuth and his Stanford graduate students.
 It tries to emulate a mathematician's style of handwriting mathematical entities on a blackboard, which is upright rather than italic.
 It blends very well with other typefaces made by Hermann Zapf, such as Palatino, Aldus and Melior, but very badly with the default TeX font Computer Modern.
 All the alphabets were implemented with the computer-assisted design system Metafont developed by Knuth.
 Zapf designed and drew the Euler alphabets in 1980–81 and provided critique and advice of digital proofs in 1983 and later.
 The typeface family is copyright by American Mathematical Society, 1983.
 Euler Metafont development was done by Stanford computer science and/or digital typography students; first Scott Kim, then Carol Twombly and Daniel Mills, and finally David Siegel, all assisted by John Hobby.
 Siegel finished the Metafont Euler digitization project as his M.S. thesis in 1985.
Thea Roland or The Adventure of Thea Roland (German: Das Abenteuer der Thea Roland) is a 1932 German comedy film directed by Henry Koster and starring Lil Dagover, Hans Rehmann and Margarete Kupfer.
 The film marked the directorial debut of Koster, who was forced to emigrate from Germany by the Nazi party following his next film and later went on to be a leading Hollywood director.
 Billy Wilder may have also worked on the screenplay, although he remained uncredited.