|Annu. Rev. Astron. Astrophys. 1991. 29:
Copyright © 1991 by Annual Reviews Inc. All rights reserved
Traditional work was contributed by single-slit optical spectroscopy, and little needs to be added with regards to this well-established technique (Sandage 1975). New detectors have appeared and data reduction techniques have benefited in the past decade from the definition of new methods (Tonry & Davis 1979, Larsen et al 1983). However, most important progress has been made in the area of multiobject spectroscopy, as well as in that of radio spectroscopy, which we choose to discuss in some detail.