This is first mentioned in the novelisation of "Remembrance of the Daleks" by Ben Aaronovitch and subsequently taken up in the spin-off media, particularly the Virgin New Adventures books and the "Doctor Who Magazine" comic strip. Davros uses the title "Destroyer of Worlds" to describe the Doctor in "Journey's End" (2008). In the Virgin New Adventures novel "Love and War", the Doctor is referred to as "The Oncoming Storm" by the Draconians (whose word for it is "Karshtakavaar"); according to the episode "The Parting of the Ways" (2005), the same title is used by the Daleks. The Doctor refers to himself as "The Oncoming Storm" in "The Lodger" (2010). In "Asylum of the Daleks" (2012), it is stated that Daleks refer to the Doctor as "The Predator". The Virgin New Adventure "Zamper" establishes that the Chelonians refer to him as "Interfering Idiot". The programme has occasionally toyed with the Doctor's identity (or lack thereof). In the first part of "The Mysterious Planet" (1986), the Doctor suggests writing a thesis on "Ancient Life on Ravolox, by Doctor...", but is interrupted by his companion Peri. In "The Armageddon Factor", the Time Lord Drax addresses the Fourth Doctor as "Thete", short for "Theta Sigma". Later, in "The Happiness Patrol" (1988), this was clarified as a nickname from the Doctor's university days; he is called by this name again in the Paul Cornell novel "Goth Opera." In "Remembrance of the Daleks", the Seventh Doctor produces a calling card with a series of pseudo-Greek letters inscribed on it (as well as a stylised question mark). This may be a reference to "The Making of Doctor Who" (1972), by Terrance Dicks and Malcolm Hulke, which claims that the Doctor's true name is a string of Greek letters and mathematical symbols. The question mark motif was common throughout the 1980s, in part as a branding attempt. Beginning with season eighteen, the Fourth through Seventh Doctors all sported costumes with a red question mark motif (usually on the shirt collars, except for the Seventh Doctor – it appeared on his pullover and in the shape of his umbrella handle). In the 1978 serial "The Invasion of Time", the Fourth Doctor is asked to sign a document; although the signature itself is not directly seen on screen, his hand movements clearly indicate that he signs it with a question mark.