@Book{GardnerKoschmieder1963,
author  = "Gardner, Johann von [Sonst.] and Koschmieder, Erwin [Sonst.]",
title   = "Ein handschriftliches Lehrbuch der altrussischen Neumenschrift. Text",
year    = "1963",
address = "München",
series  = "Abhandlungen",
volume  = "N.F., 57",
url     = "https://publikationen.badw.de/en/003835082",
}