@Book{Lenz1951,
author  = "Lenz, Hanfried",
title   = "Abschätzung einiger trigonometrischen Summen",
year    = "1951",
address = "München",
series  = "Sitzungsberichte",
volume  = "1950,8.",
url     = "https://publikationen.badw.de/en/003383644",
}