Article date: Jan 1961
Article title: In which the author chats again with Dr. Matrix, numerologist extraordinary
Mathematical Games column? Y
Book: 4. The Magic Numbers of Dr. Matrix
Chapter: 2. Los Angeles
This data confirmed? yes
Notes
Peter Rowlett (5 September 2022):
Peter Rowlett initial guess (Very uncertain)
Peter Rowlett (29 October 2023):
I have seen this chapter and column side-by-side and they match.