@Book{Zettler1973,
author  = "Zettler, Friedrich",
title   = "Biologische Aspekte zu einem mathematischen Grundlagenproblem",
year    = "1973",
address = "München",
series  = "Sitzungsberichte",
volume  = "1972,8",
url     = "https://publikationen.badw.de/en/003384317",
}