The spiral structure of our galaxy : International Astronomical Union Symposium No. 38 held in Basel, Switzerland, August 29-September 4, 1969 - International Astronomical Union. Symposium 1969 : Basel, Switzerland); Becker, W.; Contopoulos, George, 1928-; International Astronomical Union (Dordrecht, Holland : D. Reidel Publ. Co., 1970)
Keywords: Milky Way -- Congresses; Spiral galaxies -- Congresses