O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. (2002). «Knots in Nearby Planetary Nebulae». The Astronomical Journal123 (6): 3329–3347. doi:10.1086/340726. CS1 maint: Multiple names: authors list (link)
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O'Dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; Burkert, A. (2002). «Knots in Nearby Planetary Nebulae». The Astronomical Journal123 (6): 3329–3347. doi:10.1086/340726. CS1 maint: Multiple names: authors list (link)
