@book { DieBERGFormel,
    title = "Die B-E-R-G-Formel",
    subtitle = "Bewegung, Ernährung, Regeneration, Geist. Das Manuel-Eckardt-Programm, das dein Leben verändert",
    author = "Manuel {Eckardt}",
    year = "2021",
    publisher = "humboldt",
    address = "Hannover, Deutschland",
    url = "https://schluetersche.openpublishing.com/document/963200"
}