1
The Physics and Chemistry of Interstellar Molecular Clouds [E-Book] : Proceedings of the 2nd Cologne-Zermatt Symposium Held at Zermatt, Switzerland, 21–24 September 1993 /
2
The Physics and Chemistry of Interstellar Molecular Clouds: mm and Sub-mm Observations in Astrophysics [E-Book] : Proceedings of a Symposium Held at Zermatt, Switzerland, 22–25 September 1988 to Commemorate the 600th Anniversary of the University of Cologne and the 20th Anniversary of the Gornergrat Observatory /