Question: What is the first published date of the pulp magazine by the journalist H. L. Mencken where Chandler's early short stories appeared?

Context paragraphs:
Raymond Chandler: Raymond Thornton Chandler (July 23, 1888 – March 26, 1959) was an American novelist and screenwriter.  In 1932, at the age of forty-four, Chandler became a detective fiction writer after losing his job as an oil company executive during the Great Depression.  His first short story, "Blackmailers Don't Shoot", was published in 1933 in "Black Mask," a popular pulp magazine.  His first novel, "The Big Sleep", was published in 1939.  In addition to his short stories, Chandler published seven novels during his lifetime (an eighth, in progress at the time of his death, was completed by Robert B. Parker).  All but "Playback" have been made into motion pictures, some more than once.  In the year before his death, he was elected president of the Mystery Writers of America.  He died on March 26, 1959, in La Jolla, California.

Dilvish, the Damned: Dilvish, the Damned is a collection of fantasy stories by American writer Roger Zelazny, first published in 1982.  Its contents were originally published as a series of separate short stories in various fantasy magazines. Prior to publication, Zelazny's working title for the book was "Nine Black Doves".  The working title was later re-used for the fifth volume of "The Collected Short Stories of Roger Zelazny" collection, as a tribute to Dilvish.  The storyline begun in this collection was resolved in the novel "The Changing Land", which was published before the other "Dilvish" stories appeared in book form.

H. Bedford-Jones: Henry James O'Brien Bedford-Jones (1887–1949) was a Canadian historical, adventure fantasy, science fiction, crime and Western writer who became a naturalized United States citizen in 1908.  After being encouraged to try writing by his friend, writer William Wallace Cook, Bedford-Jones began writing dime novels and pulp magazine stories.  Bedford-Jones was an enormously prolific writer; the pulp editor Harold Hersey once recalled meeting Bedford-Jones in Paris, where he was working on two novels simultaneously, each story on its own separate typewriter.  Bedford-Jones cited Alexandre Dumas as his main influence, and wrote a sequel to Dumas' "The Three Musketeers", "D'Artagnan" (1928).  He wrote over 100 novels, earning the nickname "King of the Pulps".  His works appeared in a number of pulp magazines.  Bedford-Jones' main publisher was "Blue Book" magazine; he also appeared in "Adventure", "All-Story Weekly", "Argosy", "Short Stories", "Top-Notch Magazine", "The Magic Carpet", "Golden Fleece", "Ace-High Magazine", "People's Story Magazine", "Hutchinson's Adventure-Story Magazine", "Detective Fiction Weekly", "Western Story Magazine", and "Weird Tales".

Carl Richard Jacobi: Carl Richard Jacobi (July 10, 1908 – August 25, 1997) was an American journalist and author.  He wrote short stories in the horror and fantasy genres for the pulp magazine market, appearing in such pulps of the bizarre and uncanny as Thrilling, "Ghost Stories", Startling Stories, Thrilling Wonder Stories, Planet Stories and Strange Stories.  He also write stories crime and adventure which appeared in such pulps as Thrilling Adventures, "Complete Stories", Top-Notch, Short Stories, The Skipper, Doc Savage, and "Dime Adventures Magazine".  He also produced some science fiction, mainly space opera, published in such magazines as Planet Stories.  He was one of the last surviving pulp-fictioneers to have contributed to the legendary American horror magazine "Weird Tales" during its "glory days" (the 1920s and 1930s).  His stories have been translated into French, Swedish, Danish and Dutch.

Black Mask (magazine): Black Mask was a pulp magazine first published in April 1920 by the journalist H. L. Mencken and the drama critic George Jean Nathan.  The magazine was one of several money-making publishing ventures to support the prestigious literary magazine "The Smart Set", which Mencken edited, and which had operated at a loss since at least 1917.  Under their editorial hand, the magazine was not exclusively a publisher of crime fiction, offering, according to the magazine, "the best stories available of adventure, the best mystery and detective stories, the best romances, the best love stories, and the best stories of the occult."  The magazine's first editor was Florence Osborne (credited as F. M. Osborne).

Philip Marlowe: Philip Marlowe is a fictional character created by Raymond Chandler.  Marlowe first appeared under that name in "The Big Sleep", published in 1939.  Chandler's early short stories, published in pulp magazines like "Black Mask" and "Dime Detective", featured similar characters with names like "Carmady" and "John Dalmas".

Theodore Tinsley: Theodore A. Tinsley (October 27, 1894 – March 3, 1979) was an American author who primarily wrote mystery stories.  Tinsley wrote 27 stories featuring The Shadow for "The Shadow Magazine" pulp magazine.  He also created Carrie Cashin, one of the first female detectives in pulp fiction, who appeared in Street & Smith's "Crimebuster" pulp magazine.  An early series he wrote is the "Amusement Inc./Scarlet Ace" series that ran over 4 different pulp magazines in the 1930s.

Arthur Leo Zagat: Arthur Leo Zagat (1896–1949) was an American lawyer and writer of pulp fiction and science fiction.  Trained in the law, he gave it up to write professionally.  Zagat is noted for his collaborations with fellow lawyer Nat Schachner.  During the last two decades of his life, Zagat wrote short stories prolifically.  About 500 pieces appeared in a variety of pulp magazines, including "Thrilling Wonder Stories", "Argosy", "Dime Mystery Magazine", "Horror Stories", "Operator No. 5" and "Astounding".  Zagat also wrote the "Doc Turner" stories that regularly appeared in "The Spider" pulp magazine throughout the 1930s, and wrote for "Spicy Mystery Stories" as "Morgan LaFay".  A novel, "Seven Out of Time", was published by Fantasy Press in 1949, the year he died.

Margie Harris: Margie Harris (birth and death dates unknown) was a pulp writer from 1930-39.  She was one of the most popular authors in the short-lived gang pulp genre.  Even in an era of hardboiled crime fiction, her stories were unusually hard-edged and bitter.  Her best work includes ingenious plotting, remorselessly violent characters, and colorful underworld argot.  Most of her early stories appeared in the Harold Hersey-published pulp magazines "Gangster Stories", "Mobs", "Prison Stories", "Racketeer Stories", and "Gangland Stories".  When Hersey sold off his assets, Harris continued to appear in the successor to "Gangster Stories", "Greater Gangster Stories".

The Runaway Skyscraper: "The Runaway Skyscraper" is a science fiction short story by American writer Murray Leinster, first appeared in the February 22, 1919 issue of "Argosy" magazine.  Although Leinster had been appearing regularly in "The Smart Set" and pulp magazines such as "Argosy" and "Short Stories" for three years, "The Runaway Skyscraper" was his first published science fiction story (or more accurately, scientific romance, since Hugo Gernsback had yet to coin the phrase "science fiction").  Gernsback would reprint the story in the third issue of his science fiction pulp magazine "Amazing Stories" in June 1926.

Supporting paragraphs: Philip Marlowe Black Mask (magazine)
Answer: April 1920