It also appears to originate from Theodore von Kármán (1957): "Everyone knows it takes a woman nine months to have a baby. But you Americans think if you get nine women pregnant, you can have a baby in a month."
I first heard it from Fred Brooks in Mythical Man Month. But it's even funnier if it came from Theodore von Karman. A lot of HNers will know him from KSP as the namesake of the Karman line, the boundary between atmosphere and space, typically set at 100km above mean sea level.
* https://en.wikipedia.org/wiki/Brooks%27s_law * https://en.wikiquote.org/wiki/Fred_Brooks
It also appears to originate from Theodore von Kármán (1957): "Everyone knows it takes a woman nine months to have a baby. But you Americans think if you get nine women pregnant, you can have a baby in a month."