Article date: Jun 1970
Article title: Elegant triangle theorems not to be found in Euclid
Mathematical Games column? Y
Book: 9. Mathematical Circus
Chapter: 5. Elegant Triangles
This data confirmed? yes
Notes
Peter Rowlett (27 August 2022):
Peter Rowlett initial guess (Uncertain)
Peter Rowlett (30 October 2023):
I have seen this chapter and column side-by-side and they match.