@book { SelectionModelsforNonignorableMissingData,
    title = "Selection Models for Nonignorable Missing Data",
    author = "Sandro {Scheid}",
    year = "2005",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099354"
}