@Book{Hertwig1903,
author  = "Hertwig, Richard von",
title   = "Ueber Wesen und Bedeutung der Befruchtung",
year    = "1903",
address = "München",
series  = "Sitzungsberichte",
volume  = "1902,5",
url     = "https://publikationen.badw.de/en/003388894",
}