Published in "The Analysis of Emission Lines", ed. R. E. Williams, Cambridge University Press, 1995

Abstract. A review of some aspects related to the abundance determinations of planetary nebulae, galactic H II regions and extragalactic H II regions is presented. The effect of the temperature structure of gaseous nebulae on the abundance determinations is explored. The relevance of abundance determinations to some aspects of the study of the evolution of stars, galaxies and the universe is discussed.

Table of Contents

INTRODUCTION

TEMPERATURE STRUCTURE

PLANETARY NEBULAE

The Helium Abundance and Temperature Variations

GALACTIC H II REGIONS

EXTRAGALACTIC H II REGIONS

CONCLUSIONS

REFERENCES