Line-continuum correlations: There are many papers on this subject. See for example Baldwin, Gaskell and Wampler (1989), Joly (1987b) and references therein.
Line width vs. continuum luminosity: See Wandel and Yahil (1985), Joly (1987b), Mathews and Wampler (1985), Busko and Steiner (1989). The relation of the line width with the compact/extended radio luminosity ratio is discussed in Wills and Browne (1986). Some papers discussing M/L in AGNs, using line width and ionization parameters, are: Wandel and Yahil (1985), Joly et al. (1985), Wandel and Mushotzky (1986), Padovani et al. (1988) and Netzer (1989).
Thin disk models: For theoretical disk continua see Czerny and Elvis (1987), Laor and Netzer (1989), Sun and Malkan (1989), Laor (1990) and references therein. The calculations used here are from Laor and Netzer (1989) and Laor (1990). For the polarization properties of massive disks see Laor, Netzer and Piran (1990) and references therein. Recent papers on the fitting of AGN continua by disk models are Sun and Malkan (1989), Czerny and Elvis (1987) and Laor (1990).
The Baldwin relationship: The original paper is by Baldwin (1977). Some more observational studies are described in Wampler et al. (1984), Osmer and Smith (1980), Baldwin, Wampler and Gaskell (1989) and Kinney et al (1990). The Baldwin relation in individual objects is discussed in Wamsteker and Collina (1986), Kinney et al (1990) and Edelson et al (1990). Theoretical discussion can be found in Mushotzky and Ferland (1984, dependence on U and the covering factor), Murdoch (1983, line and continuum variability) and Netzer (1985, thin disks).