Ackroyd, Heather/Harvey, Dan: Beuys’ Acorns. In: Antennae: The Journal of Nature in Visual Culture 17/Why Look at Plants? (2011). Internet: http://www.antennae.org.uk/download/i/mark_dl/u/4012379076/4607883684/ANTENNAE%20ISSUE%2017.docx.pdf. S. 63–71.