O'Dell, C.R.; Ferland, G.J.; Porter, R.L.; van Hoof, P.A.M. (2011). "Physical Conditions in Barnard's Loop, Components of the Orion-eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium". The Astrophysical Journal. 733 (1): 9. arXiv:1103.2789. Bibcode:2011ApJ...733....9O. doi:10.1088/0004-637X/733/1/9. S2CID5019523.
O'Dell, C.R.; Ferland, G.J.; Porter, R.L.; van Hoof, P.A.M. (2011). "Physical Conditions in Barnard's Loop, Components of the Orion-eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium". The Astrophysical Journal. 733 (1): 9. arXiv:1103.2789. Bibcode:2011ApJ...733....9O. doi:10.1088/0004-637X/733/1/9. S2CID5019523.
O'Dell, C.R.; Ferland, G.J.; Porter, R.L.; van Hoof, P.A.M. (2011). "Physical Conditions in Barnard's Loop, Components of the Orion-eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium". The Astrophysical Journal. 733 (1): 9. arXiv:1103.2789. Bibcode:2011ApJ...733....9O. doi:10.1088/0004-637X/733/1/9. S2CID5019523.
Barnard, E. E. (1894). "The great photographic nebula of Orion, encircling the belt and theta nebula". Popular Astronomy. 2: 151–154. Bibcode:1894PA......2..151B.
O'Dell, C.R.; Ferland, G.J.; Porter, R.L.; van Hoof, P.A.M. (2011). "Physical Conditions in Barnard's Loop, Components of the Orion-eridanus Bubble, and Implications for the Warm Ionized Medium Component of the Interstellar Medium". The Astrophysical Journal. 733 (1): 9. arXiv:1103.2789. Bibcode:2011ApJ...733....9O. doi:10.1088/0004-637X/733/1/9. S2CID5019523.