3C_20
3C_20
Thực đơn
3C_20Liên quan
3C 20 3C 273 3C 244.1 3C 279 3C 305 3C 401 3C 249.1 3C 268.3 3C 288 3C 212Tài liệu tham khảo
WikiPedia: 3C_20 http://nedwww.ipac.caltech.edu/ http://simbad.u-strasbg.fr/simbad/sim-id?protocol=... http://www.wikisky.org/?ra=0.719225&de=52.05930555... http://www.jb.man.ac.uk/atlas/object/3C20.html https://ui.adsabs.harvard.edu/abs/1994A&A...286......