I came across a fascinating thread on ChthulhuWho1's Blog in which downloads of a discussion on this subject was made in 1978 at the 36th World Science Fiction Convention in Phoenix. On the panel were Fritz Leiber Jnr, Professor Dirk W. Mosig, Professor Donald R. Burleson, J. Vernon Shea, and S.T. Joshi. I have never had the chance to hear the late Fritz Leiber before, and it is great that someone has been able to make decent recordings of this available online, especially when the subject under discussion was HPL.
These are links to the downloads:
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