the interesting thing I found when I tried to track it down is that all the sources I could find were people like Deming and Taylor saying "it's absolutely not true that can only manage what you measure, why do people keep saying this when I have it clearly printed on my t-shirt"
Comments
"X isn't true"
"Who said it was?"
"It's a widely-known aphorism"
"Who started it?"
"It doesn't matter. I've already told you it isn't true"