Question: Lionel Friedberg and Ralph Staub, have which mutual occupations?

full_context: Document 1: John M. Stahl: John Malcolm Stahl (January 21, 1886 – January 12, 1950) was an American film director and producer.
Document 2: Ralph Ince: Ralph Ince (January 16, 1887 – April 10, 1937) was an American pioneer film actor, director and screenwriter whose career began near the dawn of the silent film era. Ralph Ince was the brother of John Ince and Thomas H. Ince.
Document 3: Screen Snapshots: Screen Snapshots were a series of documentary short subjects produced by Columbia Pictures between 1924 and 1958. They featured behind-the-scenes footage of Hollywood stars of the day at various Hollywood events or parties. From about 1930, these short documentaries were almost exclusively written, produced and directed (and occasionally edited and narrated) by Ralph Staub, until the series was discontinued in 1958. They usually ran for 9 or 10 minutes and were shown in cinema theatres like newsreels alongside main features.
Document 4: Malcolm St. Clair (filmmaker): Malcolm St. Clair (May 17, 1897 – June 1, 1952), also known as Mal St Clair, was a Hollywood film director, writer, producer and actor.
Document 5: Mel Stuart: Mel Stuart (born Stuart Solomon; September 2, 1928 – August 9, 2012) was an American film director and producer, who often worked with producer David L. Wolper, whose production firm he worked for 17 years, before going freelance.
Document 6: Ralph Staub: Ralph Staub (July 21, 1899 in Chicago, Illinois – October 22, 1969, Los Angeles, California) was a movie director, writer and producer.
Document 7: Lionel Friedberg: Lionel Friedberg is a documentary film director, producer and writer who has written or produced films for Animal Planet, CBS, PBS, the History Channel, the Discovery Channel and National Geographic Channel. He has 18 credits as Director of Photography on feature motion pictures, and has worked all over the world on both dramatic and nonfiction productions.
Document 8: Ray Stark: Ray Stark (October 3, 1915 – January 17, 2004) was one of the most successful and prolific independent film producers in postwar Hollywood. Highly tenacious and intelligent, Stark’s background as a literary and theatrical agent groomed him to produce some of the most dynamic and profitable films of the 1960s, 1970s, 1980s, and 1990s, such as "The World of Suzie Wong" (1961), "West Side Story" (1961), "The Misfits" (1961), "Lolita" (1962), "The Night of The Iguana" (1964), "Reflections in a Golden Eye" (1967), "Funny Girl" (1968), "The Goodbye Girl" (1977), "The Toy" (1982), "Annie" (1982), and "Steel Magnolias" (1989).
Document 9: Aaron Lubarsky: Aaron Lubarsky is a documentary filmmaker known for his work on the HBO documentary "Journeys with George", the PBS documentary "Seoul Train" and "Sportsfan". After graduation from Stanford University's Documentary Film Program, he worked as a documentarian at Lucasfilm on "The Making Of ". In 2005, he founded Flicker Flacker Films, specializing in non-fiction production. He lives and works in New York.
Document 10: Ron Fricke: Ron Fricke is a North American film director and cinematographer, specializing in time-lapse photography and large format cinematography. He was the director of photography for "Koyaanisqatsi" (1982) and directed the purely cinematic non-verbal non-narrative feature "Baraka" (1992). He designed and used his own 65
Document 11: Hardy Jones: Hardy Jones is a wildlife and conservation filmmaker. He began his career in radio at WNOE in New Orleans and has worked for United Press International, The Peruvian Times, and CBS News. He has been a television documentary producer since 1978 and has produced over 75 films for PBS, Discovery, TBS, and National Geographic. His first film, entitled DOLPHIN, depicts a school of spotted dolphins residing 40 miles north of Grand Bahama island. Since 1978 Jones has returned countless times to the Bahamas to visit these dolphins and film them. Some of the dolphins have become internationally famous. Chopper, a 27-year-old male, was filmed by Jones for the first time in 1979 and appeared in the 2005 PBS film "The Dolphin Defender".
Document 12: John Cork: An avid James Bond fan, Cork has produced, written, and directed thirty documentaries along with Bruce Scivally for MGM's releases of the James Bond films on DVD (can be seen on the Ultimate Edition 2 Disc James Bond DVDs). As an author, he and Scivally have written the biographies of Ian Fleming, Cubby Broccoli, and Harry Saltzman. Collectively, they have conducted over one hundred and fifty interviews with the creative talents behind the 007 films. They also contributed to "The Ultimate James Bond: An Interactive Dossier", a CD-ROM for MGM Interactive.
Document 13: Ralph Nelson: Ralph Nelson (August 12, 1916 – December 21, 1987) was an American film and television director, producer, writer, and actor. He was best known for directing the Oscar winning films "Lilies of the Field" (1963), "Father Goose" (1964), and "Charly" (1968).
Document 14: Sandesh Kadur: National Geographic Explorer Sandesh Kadur is a Wildlife Film Maker and Conservation Photographer known for his contributions to Planet Earth II. Sandesh's films have been shown on television networks including National Geographic Channel, BBC, Discovery Channel and Animal Planet.
Document 15: A Sacred Duty: A Sacred Duty, subtitled "Applying Jewish values to help heal the world," is a 2007 60-minute documentary from Jewish Vegetarians of North America (JVNA), written and produced by Lionel Friedberg. The film focuses on Jewish teachings about caring for the earth, treatment of animals, and the environment, with a focus on vegetarianism. Interviews with rabbis, activists, and scholars are interspersed with footage and stills illustrating the points being discussed.
ground_truth: director, writer and producer