Martin Gardner: Dr. MATRIX and other annotated works

https://en.wikipedia.org/wiki/Martin_Gardner#Annotated_works

https://en.wikipedia.org/wiki/Irving_Joshua_Matrix

In his January 1960 Mathematical Games column, Gardner introduced the fictitious "Dr. Matrix" and wrote about him often over the next two decades. Dr. Matrix was not exactly a pen name, although Gardner did pretend that everything in these columns came from the fertile mind of the good doctor.
https://en.wikipedia.org/wiki/Martin_Gardner#Pen_names

https://blog.world-mysteries.com/modern-world/lincoln-kennedy-strange-coincidences/

https://www.goodreads.com/book/show/715594.The_Magic_Numbers_of_Dr_Matrix

https://www.cut-the-knot.org/books/matrix/flap.shtml#