Old, but very good article on Singleton (and OO) misunderstand/misuse. From my opinion, a second edition (e.g. "Patterns revisited") of the Patterns book is necessary, though it's horrible that Mr. Vlissides has passed away.
K. Sung, M. Panitz, S. Wallace, R. Anderson, и J. Nordlinger. SIGCSE '08: Proceedings of the 39th SIGCSE technical symposium on Computer science education, стр. 300--304. New York, NY, USA, ACM, (2008)