Article date: Dec 1956
Article title: Flexagons
Mathematical Games column? N
Book: 1. Mathematical Puzzles and Diversions
Chapter: 1. Hexaflexagons
This data confirmed? yes
Notes
Peter Rowlett (27 August 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (27 August 2022):
Note: not a Mathematical Games column, so may not be collected in these books
Peter Rowlett (24 October 2023):
I have seen this chapter and column side-by-side and they match.