Article date: Jan 1968
Article title: The beauties of the square, as expounded by Dr. Matrix to rehabilitate the hippie
Mathematical Games column? Y
Book: 4. The Magic Numbers of Dr. Matrix
Chapter: 10. Squaresville
This data confirmed? yes
Notes
Peter Rowlett (5 September 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (29 October 2023):
I have seen this chapter and column side-by-side and they match.