Gorgas, J. & Efstathiou, G. 1987, in de Zeeuw 1987, p. 189.
Line-strength gradients have been measured in a sample of 15 early-type galaxies. The line-strength measures include the Mg2 index and the equivalent widths of H-beta and two iron blends at 5270 A and 5335 A. In most of the galaxies, gradients in the metallic line-strengths are found. However, the gradients vary markedly from object to object and do not correlate strongly with other parameters such as total luminosity, rotation, etc. A comparison of the line-strengths in the outer parts of these galaxies with galactic globular clusters suggests relatively modest abundance gradients in early-type galaxies.