Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page There's Plenty of Room at the Bottom:

"

As a thought experiment, he proposed[citation needed] developing a set of one-quarter-scale manipulator hands controlled by the hands of a human operator, to build one-quarter scale machine tools analogous to those found in any machine shop. This set of small tools would then be used by the small hands to build and operate ten sets of one-sixteenth-scale hands and tools, and so forth, culminating in perhaps a billion tiny factories to achieve massively parallel operations. He uses the analogy of a pantograph as a way of scaling down items. This idea was anticipated in part, down to the microscale, by science fiction author Robert A. Heinlein in his 1942 story Waldo.[2]