1. Sykes, R. E. Midcars: Minnesota interaction data coding and reduction system. Minneapolis, Minn: University of Minnesota. April 1971.
2. Sykes, R. E. A design for observer sampling of member interaction in a large, spontaneous group. Minneapolis, Minn: Minnesota Systems Research and University of Minnesota, 1976.
3. Sykes, R. E., &Wallen, D. A code for the study of police-civilian interaction: Police IV. Minneapolis, Minn: Minnesota Systems Research and University of Minnesota, 1974.
4. Sykes, R. E., &Whitney, F. Systematic observation utilizing the Minnesota interaction data coding and reduction system.Behavioral Science, March 1969.