The Battle of Hearts is a 1916 American silent drama film written and directed by Oscar Apfel, and produced and distributed by Fox Film Corporation.
 It starred William Farnum and Elda Furry (later known as Hedda Hopper).
 The story was by Frances Marion, then still an actress herself.
 This is Hopper's first motion picture.
Phil for Short is a 1919 silent film comedy directed by Oscar Apfel and starring Evelyn Greeley.
 It was produced and distributed by World Film Company.
Alberto de Almeida Cavalcanti (February 6, 1897 – August 23, 1982) was a Brazilian-born film director and producer.
The Squaw Man (known as The White Man in the UK) is a 1914 silent western drama film starring Dustin Farnum and directed by Cecil B. DeMille and Oscar Apfel.
 It was DeMille's directorial debut.
Peer Gynt is a surviving 1915 American fantasy silent film directed by Oscar Apfel and Raoul Walsh and written by Oscar Apfel and Henrik Ibsen.
 The film stars Cyril Maude, Myrtle Stedman, Fanny Stockbridge, Mary Reubens, Mary Ruby and Winifred Bryson.
 The film was released on September 16, 1915, by Paramount Pictures.
The Circus Man is a 1914 silent film produced by Jesse Lasky and distributed by Paramount Pictures.
 It was directed by Oscar Apfel and written by Cecil B. DeMille from a story based on the novel "The Rose in the Ring" by George Barr McCutcheon.
 It is preserved at the Library of Congress.
Rien que les heures (English: Nothing But Time or Nothing But the Hours) is a 1926 experimental silent film by Brazilian director Alberto Cavalcanti showing the life of Paris through one day in 45 minutes.
 Cavalcanti made a similar film about Berlin the next year.
Borrowed Finery is a 1925 American silent drama film produced and released by Tiffany Pictures, and based on a story by George Bronson Howard.
 Veteran director and performer Oscar Apfel directed a cast that includes Louise Lorraine, Hedda Hopper, Lou Tellegen and Ward Crane.
The Lion's Mouse (Dutch: "De leeuw en de muis" ) is a 1923 British-Dutch silent crime film directed by Oscar Apfel.
Oscar C. Apfel (January 17, 1878 – March 21, 1938) was an American film actor, director, screenwriter and producer.
 He appeared in 167 films between 1913 and 1939, and also directed 94 films between 1911 and 1927.

Question: What two occupations do  Alberto Cavalcanti and Oscar Apfel have in common?
Answer: film director and producer