@book { PhotovoltaischeFreiflchenanlagen,
    title = "Photovoltaische Freiflächenanlagen",
    author = "Brigitte {Kallmünzer}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836605731",
    url = "https://m.diplom.de/document/225387"
}