"An Open Letter" was reprinted in the Jumping Frog book (1867) as "A
Complaint about Correspondents." It didn't make the cut for Sketches, New
and Old (1875). For a more discursive comment on children's compositions,
see "Letter from Mark Twain," 19 or 20 January 1864, Early Tales &
Sketches 1, pp. 333-38.

Bob Hirst