Grealy, M. D. (1991). Knock: Apparition Gable from 1879 to the present. Cashin Printing Services.
Chicago-referens (17:e uppl.)Grealy, Msgr Dominic. Knock: Apparition Gable from 1879 to the Present. Cashin Printing Services, 1991.
MLA-referens (8:e uppl.)Grealy, Msgr Dominic. Knock: Apparition Gable from 1879 to the Present. Cashin Printing Services, 1991.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.