@Book{Gruber1778,
author  = "Gruber, Leonhard",
title   = "L. Grubers Abhandlung von der Polhoehe",
year    = "1778",
address = "München",
series  = "Abhandlungen",
volume  = "1,2",
url     = "https://publikationen.badw.de/de/003390720",
}