At the V&A
Peter Campbell: Penguin’s 70th birthday, 2 June 2005
“... So long as Penguin had rights in most of what one class of book buyers was likely to want to read in paperback (and buyers of Penguins mostly belonged to one class), identity was an advantage. By the late 1950s other paperback publishers had authors as desirable as Penguin’s in their lists, and tentative steps towards differentiation began. Which is ... ”