@Book{Wilkens1927,
author  = "Wilkens, Alexander",
title   = "Zur Erklärung der Planetoidenlücken im Sonnensystem",
year    = "1927",
address = "München",
series  = "Sitzungsberichte",
volume  = "1927,15",
url     = "https://publikationen.badw.de/en/003390919",
}