1. F.G.W. Struve, 1860, Arc du Méridien, Vol. 1 pp. XII.
2. H.C. King, 1955, The History of the Telescope, (see Chap. 3, ref 8) gives more details of the relations between Guinand, Utzschneider and Fraunhofer.
3. A. von Oettingen, 1894, Gedächtnissrede, p. 73.
4. O.W. Struve, 1895, Erinnerung, p. 37.
5. H.C. King, 1955, The History of the Telescope, (ref. 2 above), p. 183, or see plate 2 in ref. 6 above.