@Book{Seidel1873,
author  = "Seidel, Philipp Ludwig",
title   = "Ueber einen heliographischen Apparat",
year    = "1873",
address = "München",
series  = "Sitzungsberichte",
volume  = "1873,12",
url     = "https://publikationen.badw.de/de/003392214",
}