@book { WandeldesOutboundzumInboundMarketing,
    title = "Wandel des Outbound zum Inbound Marketing",
    author = "Daniela {Schultz}",
    year = "2012",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783656338994",
    url = "https://www.hausarbeiten.de/document/205821"
}