I just lost a post chock full of elaborately researched blickies, which I have no inclination to duplicate now.
The gist of it was, this is a network of closely connected weird stories.
The David Lang story was included in two compilations of strange tales in the 1950s. Both authors were suspected of cribbing from Bierce.
There is a real life David Lang, a composer, who evidently has created an opera based on "The Difficulty of Crossing a Field." (Coincidence, or just the composer's understandable fascination with a story obliquely connected to his own name? He doesn't say.)
And Bierce himself became the subject of a disappearance legend, having apparently vanished after announcing his intention to travel to Mexico to relive his fondly-remembered soldier days.
You can easily find the links yourself by a little clever Googling.
-Glenn