Examples of the theorem being referred to as proverbial include: Why Creativity Is Not like the Proverbial Typing Monkey Jonathan W. Schooler, Sonya Dougal, Psychological Inquiry, Vol. 10, No. 4 (1999); and The Case of the Midwife Toad (Arthur Koestler, New York, 1972, page 30): "Neo-Darwinism does indeed carry the nineteenth-century brand of materialism to its extreme limits—to the proverbial monkey at the typewriter, hitting by pure chance on the proper keys to produce a Shakespeare sonnet." The latter is sourced from Parable of the Monkeys, a collection of historical references to the theorem in various formats.
Grant Morrison's Animal Man #8-26, Jonathan Woodward, "Issue #25, July '90: "Monkey Puzzles" […] The text in the typewriter is Morrison's script for this issue. The monkey, of course, is the famous one who, given an infinite amount of time, will eventually write out the complete Shakespeare, completely at random."
jstor.org
Examples of the theorem being referred to as proverbial include: Why Creativity Is Not like the Proverbial Typing Monkey Jonathan W. Schooler, Sonya Dougal, Psychological Inquiry, Vol. 10, No. 4 (1999); and The Case of the Midwife Toad (Arthur Koestler, New York, 1972, page 30): "Neo-Darwinism does indeed carry the nineteenth-century brand of materialism to its extreme limits—to the proverbial monkey at the typewriter, hitting by pure chance on the proper keys to produce a Shakespeare sonnet." The latter is sourced from Parable of the Monkeys, a collection of historical references to the theorem in various formats.
mekons.de
Mekons fansite – picture and commentary on the album and cover: "This unusual title was drawn from the axiom that, if you give a monkey a typewriter and an infinite amount of time, it would eventually produce the complete works of Shakespeare, a wry comment on the group's own musical ability. The rest of the Shakespeare quote appears on the Mekons Story". The last sentence refers to the later collection The Mekons Story, which included the song 'It Falleth Like Gentle Rain from Heaven'.
Terry Butler,
"Monkeying Around with Text", University of Alberta, Computing in the Humanities Working Papers, 2007.
The date of 1960 is given in Monkeying Around with Text, Terry Butler, University of Alberta, Computing in the Humanities Working Papers, January 2007.
XFM archives "Season 1 Vol. 6", "Do you know what he said to me? I explained it to him, I said 'You've got an infinite number of monkeys, an infinite number of typewriters, they will type the complete works of Shakespeare.' He said, 'Have they read Shakespeare?'"