Similar title to Diekmann, O., Gyllenberg, M., & Metz, J.A.J. (2007). Physiologically structured population models: Towards a general mathematical theory. In: Mathematics for Ecology and Environmental Sciences. Eds. Takeuchi, Y., Iwasa, Y., & Sato, K., Berlin Heidelberg: Springer-Verlag. 10.1007/978-3-540-34428-5_2.