1. and Numerical Taxonomy: The Principles and Practice of Numerical Classification, Freeman, San Francisco 1973, pp. 1-15.
2. in: (Ed.) Principles of Bacteriology, Virology and Immunity, Vol. 2, Systematic Bacteriology, Edward Arnold, London 1983, pp. 20-30.
3. SAB Symposium;Norris,1980
4. SAB Symposium;Kersters,1980
5. SGM Special P;Kersters,1985