@book { PriceElasticity,
    title = "Price Elasticity",
    author = "Evelyn {Friedel}",
    year = "2014",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-04294-8",
    url = "https://www.peterlang.com/document/1048042"
}