Article date: Aug 1979
Article title: The imaginableness of the imaginary numbers
Mathematical Games column? Y
Book: 14. Fractal Music, Hypercards and More...: Mathematical Recreations from Scientific American Magazine
Chapter: 17. Imaginary Numbers
This data confirmed? yes
Notes
Peter Rowlett (27 August 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (4 November 2023):
I have seen this chapter and column side-by-side and they match.