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4. Kerr, F. J., and A. W. Rodgers (eds.): The Galaxy and the Magellanic Clouds (IAU Sympos. 20). Canberra 1964.
5. Woerden, H. van (ed.): Radioastronomy and the Galactic System (IAU Sympos. 31 ). London-New York: Academic Press 1967.