1. For an overall account of PN see: Pottasch: Planetary Nebulae [84P1]
2. IAU Symp,1989
3. IAU Symp.,1993
4. Some brief summaries are: [85K, 89K2, 90P1, 94K].
5. Relationships between PN and late-stellar evolution stages have been discussed in several recent books and symposia, e.g. [90M2, 91A, 93S].