Article date: Nov 1963
Article title: A mixed bag of problems
Mathematical Games column? Y
Book: 6. Martin Gardner's Sixth Book of Mathematical Games from Scientific American
Chapter: 6. The Rigid Square and Eight Other Problems
This data confirmed? yes
Notes
Peter Rowlett (27 August 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (29 October 2023):
I have seen this chapter and column side-by-side and they match.