August Derleth: posthumous collaboration controversy

After H. P. Lovecraft's death, August Derleth wrote and published numerous stories under his own and Lovecraft's bylines, described as "posthumous collaborations". They were mostly based on story ideas from Lovecraft's Commonplace Book, and occasionally incorporated fragments written by Lovecraft, but overwhelmingly consisted of Derleth's own prose.
Lovecraft scholar S. T. Joshi commented:
==The Sixteen Stories==
The 16 stories S. T. Joshi has separated apart, which have been in the past uncritically attributed to both Derleth and Lovecraft as co-authors, or even to Lovecraft alone, are
*The Lurker at the Threshold (1945)
*"The Survivor" (1954)
*"The Ancestor" (1957)
*"The Gable Window" (1957)
*"The Lamp of Alhazred" (1957)
*"The Peabody Heritage" (1957)
*"The Shadow Out of Space" (1957)
*"Wentworth's Day" (1957)
*"The Fisherman of Falcon Point" (1959)
*"The Shuttered Room" (1959)
*"Witches' Hollow" (1962)
*"The Shadow in the Attic" (1964)
*"The Dark Brotherhood" (1966)
*"The Horror from the Middle Span" (1974)
*"Innsmouth Clay" (1974)
*"The Watchers Out of Time" (1974)
S. T. Joshi's scholarship confirmed what was known privately for many years, that none of the above works are by H. P. Lovecraft. All of them are properly to be considered works of August Derleth. 
This has no relevancy to any criticism or praise of the stories on their merits; this is a matter entirely related to authorship.
Category:August Derleth works
Category:H. P. Lovecraft works