@Book{Albrecht1959,
author  = "Albrecht, Rudolf",
title   = "Über Systeme partieller Differentialgleichungen erster Ordnung mit Cauchyschen Charakteristiken",
year    = "1959",
address = "München",
series  = "Abhandlungen",
volume  = "94",
url     = "https://publikationen.badw.de/en/003071421",
}