1. Wittgenstein (1953/2004: 165 f)
2. Gombrich (1959/1987: 4 f) uses Wittgenstein’s example to introduce his own theory on Art & Illusion. The experience of illusion is hard to describe and observe just as we notice when viewing tilting images. Mitchell (1995: 45 ff) devotes a chapter of his Picture Theory to describing the duck-rabbit which also shows the original historical context as a psychological study image to its use in the satirical journal Fliegende Blätter (Flying Sheets) and Wittgenstein’s Philosophical Investigations.
3. Cf. Cross (2007: 78 f)
4. Cf. Krippendorff (2006: 52 f)
5. Cf. Wittgenstein (2004: 166)