2012. Endangered Species: Saving Them and Ourselves. White paper commissioned by the Animals and Society Institute.
2011. The Green Foodprint: Food Choices for Healthy People and a Healthy Planet. Lafayette, CA: Print and Pixel Books.
2010. Friedman, H., Krippner, S., Riebel, L., Johnson, C. Models of Spiritual
Development. International Journal of Transpersonal Studies, 29(1), 53-70.
2007. Hiatt, K., Riebel, L., & Friedman, H. (2007). The Gap between What We Know and What We Do about Childhood Obesity: A Multi-Factor Model for Assessment, Intervention, and Prevention. Journal of Social, Behavioral, and Health Sciences, 1 (1), 1-44.