Published in "The Astrophysical Journal", 269: 438-439, 1983 June 15.

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Abstract. We follow Weedman's suggestion of a spectroscopic definition for Seyfert galaxies, to present a simple four-box classification of the forms of N galaxies. The complete types for these galaxies must include a spectroscopic parameter that would show which of the Ns are also Seyferts - and the type of the Seyfert spectra in each case.

Subject headings: galaxies: structure - galaxies: Seyfert

Table of Contents

• INTRODUCTION
• SEYFERT GALAXIES AND N GALAXIES
• THE NATURE OF THE *N...*Qn SEQUENCE
• THE EFFECT OF DISTANCE ON THE CLASSIFICATION OF N GALAXIES
• THE PROBLEM OF NUCLEAR VARIABILITY
• REFERENCES