calculus at the cej

Hi perio guys: may be someone can help me with a reference relative to the calculus at the cej. As far as i remember (from in-service exams) this article sais that after closed ( or maybe even after open flap curretage) the mostly found residual calculus was the one at the cej. I know there was one article by ZANDER JP 1953 that said: "the cej seems a favored place for a type of calculus formation which makes use of the anatomical irregularities found here." However , there was another article on experimental root planing that actually showed that periodontists missed the calculus at the cej the most.