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Bolton, J. G.; Stanley, G. J.; Slee, O. B. Positions of Three Discrete Sources of Galactic Radio-Frequency Radiation. Nature. 1949, 164 (4159): 101. Bibcode:1949Natur.164..101B. doi:10.1038/164101b0.
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Baum, S. A.; Zirbel, E. L.; O'Dea, Christopher P. Toward Understanding the Fanaroff-Riley Dichotomy in Radio Source Morphology and Power. The Astrophysical Journal. 1995, 451: 88. Bibcode:1995ApJ...451...88B. doi:10.1086/176202.
Garrington, S. T.; J. P. Leahy; R. G. Conway; RA LAING. A systematic asymmetry in the polarization properties of double radio sources with one jet. Nature. 1988, 331 (6152): 147–149. Bibcode:1988Natur.331..147G. doi:10.1038/331147a0.
Wang, J.M.; Du P.; Baldwin J.A.; Ge J-Q.; Ferland G.J.; Ferland, Gary J. Star formation in self-gravitating disks in active galactic nuclei. II. Episodic formation of broad-line regions. The Astrophysical Journal. 2012, 746 (2): 137–165. Bibcode:2012ApJ...746..137W. arXiv:1202.0062v1. doi:10.1088/0004-637X/746/2/137.
Dultzin-Hacyan, D.; Krongold Y.; Fuentes-Guridi I.; Marziani P. The Close Environment of Seyfert Galaxies and Its Implication for Unification Models. Astrophysical Journal Letters. 1999, 513 (2): L111–L114. Bibcode:1999ApJ...513L.111D. arXiv:astro-ph/9901227v1. doi:10.1086/311925.
Villarroel, B.; Nyholm A.; Karlsson T.; Comeron S.; Korn A.; Sollerman J.; Zackrisson E. AGN luminosity and stellar age - two missing ingredients for AGN unification as seen with iPTF supernovae. The Astrophysical Journal. 2017, 837 (2): 110. Bibcode:2017ApJ...837..110V. arXiv:1701.08647v1. doi:10.3847/1538-4357/aa5d5a.