- ^ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 NASA/IPAC Extragalactic Database. Results for NGC 2403. [2006-11-21]. (原始內容存檔於2011-05-14).
- ^ 2.0 2.1 2.2 Kepple, George Robert; Glen W. Sanner. The Night Sky Observer's Guide, Volume 1. Willmann-Bell, Inc. 1998: 73. ISBN 0-943396-58-1.
- ^ Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W., A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies, Astrophysical Journal Supplement 112, October 1997, 112: 315–390 [2008-03-08], (原始內容存檔於2016-01-10)