@book { PsychologischeProblemedesAlterns, title = "Psychologische Probleme des Alterns", subtitle = "The Psychological Problems of Aging", author = "Erich {Fromm} and Rainer {Funk}", year = "2016", publisher = "Edition Erich Fromm", address = "München, Deutschland", url = "https://books.openpublishing.com/document/313997" }