There are tens of thousands of regurgitations of the basic idea of including relativistic effects but very few sources that have looked directly at the necessity.<p>It was certainly included. The question of necessity, however, is another matter.<p>Once again, I must repeat that there are components of relativistic theory that are nearly indistinguishable from classical at such low proportions of C.<p>For instance, the entire relativistic doppler effect is often cited as a relatvistic effect. However, the portion of that whole large effect that is purely and uniquely relativity is miniscule because the difference between classical and relativistic are negligible at such low speeds (Super-sonic jets are dead snails covered in cold molasses compared to C)<p>Bear in mind that all the hyper-precise navigation we do within our solar system, from landing on mars to landing on a comet is PURELY NEWTONIAN.<p>(You should gasp with surprise here... I know I did when I learned that)