Essjay defended his use of the book by telling fellow Wikipedia editors in a disagreement over the editing of the article Imprimatur : `` This is a text I often require for my students , and I would hang my own Ph. D. on itâ s credibility . '' Essjay defended his use of the book by telling fellow Wikipedia editors in a disagreement over the editing of the article Imprimatur : `` This is a text I often require for my students , and I would hang my own Ph. D. on its credibility . ''