1. 1) St. Louis KO and Schulte K: Defining cluttering: The lowest common denominator. Cluttering: A Handbook of Research, Intervention and Education (edited by Ward D and Scaler Scott K), Psychology Press, East Sussex, England, pp 233-253, 2011.
2. 3) Van Riper C: Type of stutterers. The Nature of Stuttering, 2nd ed, Prentice-Hall, Englewood Cliffs, NJ, pp 249-264, 1971.
3. 4) Tiger RJ, Irvine TL and Reis RP: Cluttering as a complex of learning disabilities. Lang Speech Hear Serv Sch, 1: 3-14, 1980.
4. 5) Daly D: Helping the clutterer: Therapy considerations. Cluttering: A Clinical Perspective (edited by Myers FL and St. Louis KO), Far Communications, Leicester, England, pp 107-124, 1992.
5. 6) St. Louis KO: On defining Cluttering. Cluttering: A Clinical Perspective (edited by Myers FL and St. Louis KO), Far Communications, Kibworth, Great Britain, Reissued in 1996 by Singular, San Diego, pp 23-35, 1992.