Okay, so it was probably created in 1969 or 1970 and only published in 1971. I think you've misunderstood what we are talking about - the method by which the g

Okay, so it was probably created in 1969 or 1970 and only published in 1971. I think you've misunderstood what we are talking about - the method by which the graphic was created. Which I assume to have been a plotter fed instructions by a program that removed hidden lines from the graphs.