Moore, K.L., 1989. Before we are born. Saunders, Philadelphia.
Verhulst, J., 2003 (1999). Development Dynamics in Humans and Other Primates: Discovering Evolutionary Principles through Comparative Morphology (Translation of: Der Erstgeborene. Freies Geistesleben, Stuttgart), Adonis Press, Ghent, New York.
Van der Wal, J., 2003. Dynamic morphology and embryology. In: Bie, G van der & M. Huber, Foundations of anthroposophical medicine. Floris Books, Edinburgh, UK.