1. Literature has been grouped in reference lists of several chapters in those cases where arguments are difficult to entangle or published over several articles or books. In cases of citation the article or book involved is indicated by the reference number together with a capital Arabic letter.
2. Dullemeyer P (1974) Concepts and approaches in animal morphology. Van Gorcum Co, Assen
3. Gogelein AJF (1973) From lichtleiter to fibre optics: history of the treatment of bladder stones and cystoscopy. Boerhaave Museum, Leiden. Mededeling Rijksmuseum Geschiedenis der Natuurwetenschappen, Leiden, Nr 139
4. Murphy LJT (1972) The history of urology. C.C. Thomas Publication, Springfield
5. Vesalius A (1964) De humani corporis Fabrica libri septem. Culture et civilisation 115 Ave Grabriel Lebon. Bruxelles