I've seen this in quite a few bookshops, fairly prominently displayed which suggests that the booksellers are behind it. I'll soon be ttc and wondered if it was a useful / silly / fun one to read! The amazon link is \link{http://www.amazon.co.uk/exec/obidos/ASIN/0007213433/ref=ord_cart_shr/026-9658063-4033229?%5Fencoding=UTF8&m=A3P5ROKL5A1OLE\here}