Boscaggin, Alberto, Walter Dambrosio, and Duccio Papini. “Periodic Solutions to Relativistic Kepler Problems: A Variational Approach”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE (December 27, 2022): 33. Accessed May 26, 2026. https://journals-dev.sns.it/index.php/annaliscienze/article/view/5900.