Jack McMillen is known as the inventor. At least he was the first to show it publicly (and it's not about when it was first published but about when it was first performed). We will never know if he really was the first to come up with it, nor do we know that for any other effect ever created.
But yeah, if you would have to credit anyone, it would be him. But if you got it from another source you may very well want to credit both Jack and the person who put together that source, especially if that person did something to the original.