@book { DieRolledesSuchmaschinenmarketingimOnlineMarketing,
    title = "Die Rolle des Suchmaschinenmarketing im Online-Marketing",
    author = "Christian {Knotik}",
    year = "2012",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783656281344",
    url = "https://www.hausarbeiten.de/document/201315"
}