@book { BiomonitoringanKiefernnadelnimRheinErftKreis,
    title = "Biomonitoring an Kiefernnadeln im Rhein-Erft-Kreis",
    author = "Oliver {Paech}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836631747",
    url = "https://m.diplom.de/document/226980"
}