Beginning in 1936, many of Hammett's novelettes and stories began to appear in serialized form in various newspapers. Sometimes the stories were given new titles, sometimes not. "Girl Hunt" is a retitling of "Fly Paper," with originally appeared in the August 1929 issue of Black Mask.
These examples are from The Pittsburgh Sun-Telegraph of June 1936, The St. Louis Post-Dispatch from July 1936. They're presented here for the artwork, which was original to the serialization. In some of the Op stories, our hero was billed as "Continental Operative No. 7." Why that 7 was deemed necessary is too many for me.
If you want to read the story (and you should, because stylistically it's one of Hammett's best) you'll find Frederic Dannay's edited version in the 1945 Bestseller Mystery digest The Continental Op, the subsequent Dell mapback of the the same title, the 1966 hardcover The Big Knock-Over and the paperback editions of that volume. For the real thing, you'll have to seek out the 2001 Library of America volume Crime Stories and Other Writings, the 2016 Mysterious Press ebook The Continental Op: The Complete Case Files, or 2017's magnum opus, The Big Book of The Continental Op. One version or other of the story also appeared in the 2005 collection Vintage Hammett.
