1. The Burlington randomized trial of the nurse practitioner;Spitzer;N Engl J Med,1974
2. Nurse practitioners in primary care. I. The McMaster University educational program;Spitzer;Can Med Assoc J,1973
3. An empirical study of cluster randomization;Donner;Int J Epidemiol,1982
4. Nurse practitioners in primary care. 3. The southern Ontario randomized trial;Spitzer;Can Med Assoc J,1973
5. Financial consequences of employing a nurse practitioner;Spitzer;Ont Med Rev,1973