Oziewicz 2010, p. 13. Oziewicz, Marek (2010). "Representations of Eastern Europe in Philip Pullman's His Dark Materials, Jonathan Stroud's The Bartimaeus Trilogy, and JK Rowling's Harry Potter Series". International Research in Children's Literature. 3 (1) (International Research in Children's Literature ed.): 1–14. doi:10.3366/ircl.2010.0002.
Oziewicz 2010, p. 11. Oziewicz, Marek (2010). "Representations of Eastern Europe in Philip Pullman's His Dark Materials, Jonathan Stroud's The Bartimaeus Trilogy, and JK Rowling's Harry Potter Series". International Research in Children's Literature. 3 (1) (International Research in Children's Literature ed.): 1–14. doi:10.3366/ircl.2010.0002.