Heinzner, Peter, and Patrick Schützdeller. “The Extended Future Tube Conjecture for SO(1, N)”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 3, no. 1 (December 14, 2009): 39-52. Accessed May 28, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/35.