Sad news indeed. I was referring to one of his books on art-song here
http://r3ok.myforum365.com/index.php?topic=137.990;topicseen only last night. I've found these books invaluable, even though they must be some of the worst-edited (that's copy-edited) music books ever put out, and an absolute disgrace for a publisher as prestigious as CUP.
German speakers may enjoy
a purported quotation from Morike's 'Der Feuerreiter: "nach das Glocklein klinget nus". [properly "auch.........aus"]. At least, I think that's how it was printed: I got so disgusted with this outrage that I corrected it in my copy, never suspecting that I might ever want to reconstuct its original glory
(Please excuse absence of umlauts - can never remember how to do them here!)