@Book{Maas1905,
author  = "Maas, Otto",
title   = "Bemerkungen zum System der Medusen. Revision der Cannotiden Haeckels",
year    = "1905",
address = "München",
series  = "Sitzungsberichte",
volume  = "1904,16",
url     = "https://publikationen.badw.de/en/003395053",
}