@book { MentaltoughnessandhardinessatdifferentlevelsoffootballSportsPsychologyandCoaching,
    title = "Mental toughness and hardiness at different levels of football. Sports Psychology and Coaching.",
    author = "Mark {Atkinson}",
    year = "2013",
    publisher = "Anchor Academic Publishing",
    address = "Hamburg, Germany",
    url = "https://m.anchor-publishing.com/document/312664"
}