4.5. Recombination Lines
The Hydrogen recombination lines are covered thoroughly by Hummer and Storey (1987) and Storey and Hummer (1988), including dust opacity (Hummer and Storey 1992).
The Helium lines have recently been computed by Smits (1991), with references to previous work by Brocklehurst and others (see also, Osterbrock 1989).
Recent work on recombination lines of O II by Storey (1994) and Liu et al. (1994) extends the treatment to complex ions, based on new Opacity Project data.