The history of Key Loggers

I'm making an article about the history and evolution of Key loggers. I kinda remember key loggers was a security feature that dated as far back to the time computers were able to run back ground programs...

I need some help with internet resources or even books that will help me with my article.

I need to have proper credits for it. Thank you

(every time I search history and keyloggers, only websites that sell software pop up)