Medeiros, Alexandre, and Cleide Farias de Medeiros. “Einstein, The Physics of Toys and the Equivalence Principle”. Caderno Brasileiro de Ensino de Física 22, no. 3 (January 1, 2005): 299–315. Accessed August 31, 2024. https://periodicos.ufsc.br/index.php/fisica/article/view/6373.