I am interested in finding out who introduced code indentation, as well as when and where it was introduced.

It seems so critical to code comprehension, but it was not universal. Most Fortran and Basic code was (is?) unindented, and the same goes for Cobol.

I am pretty sure I have even seen old Lisp code written as continuous, line-wrapped text. You had to count brackets in your head just to parse it, never mind understanding it.

So where did such a huge improvement come from? I have never seen any mention of its origin.

Apart from original examples of its use, I am also looking for original discussions of indentation.