| Ion | A | C | E |
| [N II] | [3] | [9] | [1, 2] |
| [O II] | [3] | [6, 7] | [1, 4, 5] |
| [O III] | [3] | [9] | [1, 8] |
| [Ne III] | [5, 10] | [11] | [1] |
| [Ne IV] | [13, 14] | [15] | [12] |
| [Ne V] | [5, 24] | [9] | [1, 10] |
| [S II] | [16, 17] | [18] | [1, 16] |
| [S III] | [5, 19, 20, 21] | [22] | [1] |
| [Cl III] | [10, 5] | [23] | [1] |
| References: [1] Bowen (1960); [2] Williams & Livio (1995); [3] Wiese et al. (1996); [4] Fawcett (1975); [5] Kaufman & Sugar (1986); [6] Pradhan (1976); [7] McLaughlin & Bell (1993); [8] Moore (1985); [9] Lennon & Burke (1994); [10] Mendoza (1983); [11] Butler & Zeippen (1994); [12] Moore (1971); [13] Becker et al. (1989); [14] Bhatia & Kastner (1988); [15] Giles (1981); [16] Verner et al. (1996); [17] Keenan et al. (1993); [18] Ramsbottom et al. (1996); [19] Mendoza & Zeippen (1982); [20] Heise et al. (1995); [21] LaJohn & Luke (1993); [22] Galavis et al. (1995); [23] Butler & Zeippen (1989); [24] Bhatia & Doschek (1993). |