1. Anderson, Kenneth; Smith, Herbert A., Topics in Statistics for Students in Education, 1959, pp. 112–114.
2. Ausubel, David, Educational Psychology: A Cognitive View, 1962, pp. 355–365.
3. The influence of school camping on the self-concepts and social relationships of sixth grade school children.
4. Blomberg, Karlin, “Direct Experience Teaching in the Out-of-Doors,” unpublished MS thesis, University of Minnesota, 1967, pp. 1–40.