Schaeffer into the underdrawings of the Dombild Altarpiece established two guiding hands, presumably Lochner and an exceptionally talented pupil, whom she concludes was in probability the principal artist behind the Heisterbach Altarpiece. A counter view is that Lochner's workshop was producing to a deadline, and he delegated as a matter of expediency. Gallery References Notes Sources "Billinge A": Billinge, Rachel; Campbell, Lorne; Dunkerton, Jill; Foister, Susan. "A double-sided panel by Stephan Lochner". National Gallery Technical Bulletin, No. 18, 1997 Billinge B": Billinge, Rachel; Campbell, Lorne; Dunkerton, Jill; Foister, Susan, et al., "Methods and Materials of Northern European Painting in the National Gallery, 1400–1550". National Gallery Technical Bulletin Vol 18, pp. 6–55, 1997, online text Borchert, Till-Holger. Van Eyck to Dürer. London: Thames & Hudson, 2011. Campbell, Lorne. The Fifteenth-Century Netherlandish Paintings. London: National Gallery, 1998. Chapuis, Julien. Stefan Lochner: Image Making in Fifteenth-Century Cologne. Turnhout: Brepols, 2004. Chilvers, Ian. The Oxford Dictionary of Art and Artists. Oxford: Oxford University Press, 2009. Corley, Brigitte. "A Plausible Provenance for Stefan Lochner?". Zeitschrift für Kunstgeschichte, Volume 59, 1996 Emmerson, Richard K. Key Figures in Medieval Europe. London: Routledge, 2005. Kenney, Theresa. The Christ Child in Medieval Culture. Toronto: University of Toronto Press, 2012. Nash, Susie. Northern Renaissance art. Oxford: Oxford University Press, 2008. O'Neill, Robert Keating. The Art of the Book from the Early Middle Ages to the Renaissance. MA: John J. Burns Library, 2000 Richardson, Carol. Locating Renaissance Art: Renaissance Art Reconsidered. New Haven, CT: Yale University Press, 2007. Ridderbos, Bernhard; Van Buren, Anne; Van Veen, Henk. Early Netherlandish Paintings: Rediscovery, Reception and Research. Amsterdam: Amsterdam University Press, 2005. Rowlands, John. The Age of Dürer and Holbein: German Drawings 1400–1550. London: British Museum Publications, 1988. Schaefer, Iris; Von Saint-George, Caroline. "New Findings Concerning the Underdrawing of Stefan Lochner's Altarpiece of the City Patron Saints in Cologne Cathedral". Kölner Domblatt, Volume 79, 2014 Schmid, Wolfgang; Holladay, Joan. "Reviewed: 'Painting and Patronage in Cologne, 1300–1500' by Brigitte Corley". Speculum, Volume 78, No. 2, 2003 Singer, Hans W. Stories of the German Artists. Wildside Press, 2010. Smith, Jeffrey Chipps. The Northern Renaissance (Art and Ideas). London: Phaidon Press, 2004. Snyder, James. Northern Renaissance Art. Englewood Cliffs, NJ: Prentice-Hall, 1985. Stechow, Wolfgang. "A Youthful Work by Stephan Lochner". The Bulletin of the Cleveland Museum of Art, Volume 55, No. 10, 1968 Walther, Ingo. Codices Illustres: The World's most famous Illuminated Manuscripts. Berlin: Taschen, 2014. Wellesz, Emmy.