Kajitani, Kunihiko, and Yasuo Yuzawa. “The Cauchy Problem for Hyperbolic Systems With Hölder Continuous Coefficients With Respect to the Time Variable”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE 5, no. 4 (December 4, 2009): 465-482. Accessed May 28, 2025. http://20.103.181.36/index.php/annaliscienze/article/view/107.