@book { AHealthyMix,
    title = "A Healthy Mix?",
    author = "Benjamin {Heldt}",
    year = "2013",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02759-4",
    url = "https://www.peterlang.com/document/1047208"
}