The claim that equatorial locations provide optimal launch sites due to Earth's rotational velocity is a well-established principle of orbital mechanics and everyday aerospace observation requiring no citation.
The provided retrieved papers discuss unrelated topics such as remote sensing of vegetation, atmospheric coupling, planetary rovers, and lunar architectures, containing no specific empirical studies debating orbital mechanics. However, the claim itself rests on basic physics (Earth's rotational speed is highest at the equator, providing a free velocity boost to eastward-launched rockets) and is therefore classified as common knowledge that does not require academic citations.