You want a specific citation for a common practice? When something is that common there are no citations. Sets for small spaces were built big enough for the camera to fit in. Much larger spaces were built smaller to save money. Hollywood is about illusion, not reality. Besides, both exterior versions of the shuttle were built to an exact scale. The small model and associated hanger were built at a specific scale that makes the shuttle 22' long and the full size set piece was 22' long. If the intended scale was something else, the small model and hanger would have been built to the intended scale. Instead they were built to a specific scale that makes the shuttle 22' long. The set is the only thing that does not match and coupled with the practice of building small spaces large enough for the camera to shoot easily, there is no need for any citation to be certain that is what they did.