1. Agerhem, H., & Nilsson H. J., Inventors (1981). Substrate composition and use thereof. United States Patent US 4,284,719.
2. Foodborne illness in the refrigerator;Anonymous,2007
3. Arens, R. P., Birkholz, R. D., Johnson, D. L., Labuza, T. P., Larson, C. L., & Yarusso, D. J., Inventors (1997). Time–temperature integrating indicator device. United States Patent US 5,667,303.
4. Blixt, K. G., Tornmarck, S. I. A., Juhlin, R., Salenstedt, K. R., Tiru, M., Inventors (1977). Enzymatic substrate composition adsorbed on a carrier. United States Patent US 4,043,871.
5. Applicability of an enzymatic time-temperature-integrator as a quality indicator for mushrooms in the distribution chain;Bobelyn;Postharvest Biology and Technology,2006