@book { ExperimentelleUntersuchungzueinemSperrpreisDuopol,
    title = "Experimentelle Untersuchung zu einem Sperrpreis-Duopol",
    author = "Nikolas {Beutin}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832400156",
    url = "https://m.diplom.de/document/215974"
}