@book { NationalParksandTourism,
    title = "National Parks and Tourism",
    author = "Christian {Eilzer} and Bernd {Eisenstein} and Wolfgang G. {Arlt}",
    year = "2021",
    publisher = "Meidenbauer",
    address = ", Germany",
    url = "https://www.peterlang.com/document/1105768"
}