Dr J. Landi Dessy, Director of the Astronomical Observatory, Cordoba, Argentina, invited the International Astronomical Union to hold a Symposium in Cordoba in connection with the celebration of the Centennial of the Cordoba Observatory; the date of foundation is October 24, 1871. He proposed that the Symposium should deal with Spectral Classification and Multicolour Photometry as seven years had elapsed since the Symposium No. 24 in Saltsj6baden, and much development had occurred in the field. The invitation and the proposal were accepted by the IAU, and the Symposium was held in Villa Carlos Paz, near Cordoba, between October 18 and October 24, 1971. It was attended by about 50 scientists representing Argentina, Canada, Chile, Den mark, France, Germany, Italy, Mexico, Sweden, Switzerland, U.K., U.S.A., Vatican City State and Venezuela. The Symposium was divided into four sessions: 1. Classification of slit spectra, 2. Classification of objective-prism spectra, 3. Photometric classification, 4. Catalogues and documentation. It was decided not to include problems of calibration of absolute magnitudes and temperatures of stars but to refer this to a separate symposium. The contents of the present volume follow closely the programmes of the individual sessions of the Symposium. All the participants at the Symposium appreciated the excellent hospitality of their Argentinian hosts and the efficient help given by the staff ofthe Cordoba Observatory.

Inhalt
The Role of Classification of Slit Spectrograms (Introductory Lecture).- Spectroscopic Criteria for the Classification of Peculiar B-type Stars with Colour-Spectrum Discrepancies.- Classification des étoiles B à partir des raies de l'hydrogèneComparaison avec d'autres classifications.- Étude des étoiles supergéantes du Grand Nuage de Magellan, leurs magnitudes absolues et couleurs.- Quantitative Spectral Classification in the BCD System for LMC Supergiants.- Photometric Investigation of IC 2944 (Abstract).- Spectral Classification Studies of Cepheids Using a Small Telescope with an Image Tube Spectrograph (Abstract).- Spectral Classification of Some Long-Period and Semi-Regular Variables Near Times of Maximum (Read by P. Rybsky).- Some Notes on Stars Near KO.- Spectroscopic Observations of the Sanduleak-Seggewiss Stars (Abstract).- On the Precision of the MK Spectral Classification System.- On the Accuracy of Spectral Classifications of Main-Sequence Stars.- Advantages and Limitations of Quantitative Spectral Classification (Read by E. Maurice).- Introductory Talk for Session on Objective Prism Spectral Classification (Introductory Lecture).- Two-Dimensional Classification of the HD Stars.- Early Results from the Michigan Southern-Hemisphere Spectral Survey (Read by C. B. Stephenson).- The Bonn Spectral Atlas: Part II.- The Present State of a Spectral Survey of the Southern Milky Way for Stars Earlier than A5.- Objective Prism Spectral Classification at the Stockholm Observatory.- The Peculiar Stars and Spectral Classification (Read by B. E. Westerlund).- Spectrophotometry of M and C Stars (Abstract and Summary).- The Spectral Classification of Southern Carbon Stars.- Automatic Classification of Objective Prism Spectra.- Microphotometry-ComputerClassification of Objective-Prism Spectra.- Blue-Infrared Narrow-Band Photometry from Objective Prism Spectra (Read by L. Gratton).- Preliminary Investigation of Quantitative Spectral Classification by Means of Objective-Prism Spectra Obtained with the Broerfelde Schmidt Telescope (Read by R. M. West).- General Remarks on Quantitative Spectral Classification (Introductory Lecture).- Applications of the UB1B2V1G Photometric System.- Classification of Early Type Stars on the Dominion Astrophysical Observatory Photometric System.- The David Dunlap Observatory (DDO) Photometric System for Classification of Late-Type Stars.- Results from Three Dimensional Spectral Classification of Population II Stars Using the DDO Photometric System.- Photometric Classification of Stars in the Vilnius Observatory.- Photometric Classification of B-Type Stars.- Multicolor Photometry of the Galactic Cluster NGC 2362.- Photoelectric Measures of H?, H? and H? in Early-Type Stars.- Narrow Band Photometry of Supergiant Stars (Abstract).- New Standards for the Spectral Classification of M Dwarfs.- The Identification of T Tauri-Like Stars by Multicolour Photometry.- Classification of Population II Stars in the RGU System.- Photometric Classification of Blue Horizontal-Branch Stars.- Some Blue Stars of Peculiar Type in the Region of the South Galactic Pole.- Quelques sous-naines dans la direction du Grand Nuage de Magellan.- Two Dimensional Spectral Classification of Early Type Stars by Low Dispersion Spectrophotometry.- Low Dispersion Spectrophotometry of Late Type Stars.- Information and Catalogues (Introductory Lecture).- Photometric Data in Machine-Readable Form.- Remark in Regard to Bidelman's Data-Bank Project (Read by C. B. Stephenson).- The Southern Objective Prism Survey (Abstract).- AMethod for Determining Radial Velocities from Objective Prism Plates.- Spectral and UBV Data for 583 Stars (Supergiants and Foreground Stars) in the Direction of the Large Magellanic Cloud (Abstract).- A Study of Interstellar Reddening at High Galactic Latitudes.- The Construction and Documentation of the Celescope Catalog.