@Book{Schmidt1899,
author  = "Schmidt, Adolf",
title   = "Mitteilungen über eine neue Berechnung des erdmagnetischen Potentials",
year    = "1899",
address = "München",
series  = "Abhandlungen",
volume  = "Bd. 19, Abth. 1 = [1]",
url     = "https://publikationen.badw.de/en/003071148",
}