References – AN 3.40: Authorities 
Readings from The Island by Ajahn Pasanno and Ajahn Amaro, Chapter 6, pp. 117-123. Read by Ajahn Amaro:
Suttas: MN 113.21; MN 137.19-20; AN 4.24.
Richard Gombrich, ‘Metaphor, Allegory, Satire,’ in How Buddhism Began: The Conditioned Genesis of the Early Teachings, pp. 86-7.
Hsin Hsin Ming, the verses of the Third Ch’an Patriarch.
Atulo, collected teachings of Ajahn Dune compiled by Ajahn Bodhinandamuni (no full English translation).
AN 3.40 in The Magic of the Mind by Bhikkhu Ñāṇananda pp. 49 & 52.