@book { InternalandExternalSourcingStrategies,
    title = "Internal and External Sourcing Strategies",
    author = "James {Tallant}",
    year = "2011",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640838004",
    url = "https://www.hausarbeiten.de/document/167300"
}