Torres-Peimbert, "The [O.sup.++]/[H.sup.+] abundance ratio in
gaseous nebulae derived from recombination lines," Astrophysical Journal Letters, vol.
2, Planetary and
Gaseous Nebulae, Enslow Publishers, Hillside, NJ., 149 pp.
[At the telescope] even the most colorful
gaseous nebulae seem to be little more than faint grey luminous smudges of light....