From Dirk Gently’s Holistic Detective Agency by Douglas Adams:
Indeed, it was not entirely clear if Reg had ever taught anybody at all and what, if anything, he would have taught them. His professorship was an obscure one, to say the least, and since he dispensed with his lecturing duties by the simple and time-honoured technique of presenting all his potential students with an exhaustive list of books that he knew for a fact had been out of print for thirty years, then flying into a tantrum if they failed to find them, no one had ever discovered the precise nature of his academic discipline. He had, of course, long ago taken the precaution of removing the only extant copies of the books on his reading list from the university and college libraries, as a result of which he had plenty of time to, well, to do whatever it was he did.
