Henry Burnand Garland, Henry Garland e Mary Garland, Piontek, Heinz, in The Oxford Companion to German Literature, Oxford University Press, 1997, ISBN978-0-19-815896-7.
Raymond Furness e Malcolm Humble, Piontek, Heinz, in A Companion to Twentieth-Century German Literature, Routledge, 2003, ISBN978-1-134-74764-1.
